tneusejgofMembers  only* 
OFFICES. 1323WALNVT 
Street     PHILADELPHIA 


THE  LIBRARY 

OF 

THE  UNIVERSITY 
OF  CALIFORNIA 


PRESENTED  BY 

PROF.  CHARLES  A.  KOFOID  AND 

MRS.  PRUDENCE  W.  KOFOID 


PLEASUEES  OF  THE   TELESCOPE 


PLEASUKES  OF  THE 
TELESCOPE 


AN  ILLUSTRATED   GUIDE   FOR  AMATEUR  ASTRONOMERS 

AND   A  POPULAR  DESCRIPTION   OF   THE   CHIEF 

WONDERS   OF   THE   HEAVENS  FOR 

GENERAL   READERS 


BY 

GARRETT  P.    SERVISS 

AUTHOR  OF  ASTRONOMY  WITH  AN  OPERA-GLASS 


1  This  being  made,  He  yearned  for  worlds  to  make 
From  other  chaos  out  beyond  our  night — 
For  to  create  is  still  God^s  prime  delight. 
The  large  moon,  all  alone,  sailed  her  dark  lake, 
And  the  first  tides  were  moving  to  her  might ; 
Then  Darkness  trembled,  and  began  to  quake 
Big  with  the  birth  of  stars,  and  when  He  spake 
A  million  worlds  leapt  into  radiant  light.1'' 

LLOYD  MIFFLIN. 


WITH  MANY  ILLUSTRATIONS 


NEW    YORK 
D.     APPLETON    AND     COMPANY 

1901 


COPYRIGHT,  1901, 
BY  D    APPLETON  AND  COMPANY. 


PREFACE 


BY  the  introduction  of  a  complete  series  of  star  maps, 
drawn  specially  for  the  use  of  the  amateur  and  dis- 
tributed through  the  body  of  the  work,  thus  facilitating 
consultation,  it  is  believed  that  this  book  makes  a  step  in 
advance  of  its  predecessors.  The  maps  show  all  of  the 
stars  visible  to  the  naked  eye  in  the  regions  of  sky  repre- 
sented, and,  in  addition,  some  stars  that  can  only  be  seen 
with  optical  aid.  The  latter  have  been  placed  in  the  maps 
as  guide  posts  in  the  telescopic  field  to  assist  those  who 
are  searching  for  faint  and  inconspicuous  objects  referred 
to  in  the  text.  As  the  book  was  not  written  for  those  who 
possess  the  equipment  of  an  observatory,  with  telescopes 
driven  by  clockwork  and  provided  with  graduated  circles, 
right  ascensions  and  declinations  are  not  given.  All  of 
the  telescopic  phenomena  described  are,  however,  repre- 
sented in  the  maps.  Star  clusters  are  indicated  by  a  con- 
ventional symbol,  and  nebulae  by  a  little  white  circle; 
while  a  small  cross  serves  to  mark  the  places  where  nota- 
ble new  stars  have  appeared.  The  relative  magnitudes  of 
the  stars  are  approximately  shown  by  the  dimensions  of 
their  symbols  in  the  maps,  the  smaller  stars  being  repre- 
sented by  white  dots  and  the  larger  by  star-shaped  figures. 

In  regard  to  binary  stars,  it  should  be  remembered 
that,  in  many  cases,  their  distances  and  angles  of  posi- 
tion change  so  rapidly  that  any  statement  concerning 
them  remains  valid  only  for  a  few  years  at  the  most. 
There  is  also  much  confusion  among  the  measurements 


vi  PLEASURES  OF  THE  TELESCOPE 

announced  by  different  authorities.  In  general,  the  most 
recent  measurements  obtainable  in  1900  are  given  in  the 
text,  but  the  observer  who  wishes  to  study  close  and  rapid 
binaries  will  do  well  to  revise  his  information  about  them 
as  frequently  as  possible.  An  excellent  list  of  double 
stars  kept  up  to  date,  will  be  found  in  the  annual  Com- 
panion to  the  Observatory,  published  in  London. 

In  the  lunar  charts  the  plan  of  inserting  the  names  of 
the  principal  formations  has  been  preferred  to  that  usually 
followed,  of  indicating  them  only  by  numbers,  accompanied 
by  a  key  list.  Even  in  the  most  detailed  charts  of  the 
moon  only  a  part  of  what  is  visible  with  telescopes  can  be 
shown,  and  the  representation,  at  best,  must  be  merely 
approximate.  It  is  simply  a  question  of  what  to  include 
and  what  to  omit;  and  in  the  present  case  the  probable 
needs  of  the  amateur  observer  have  governed  the  selec- 
tion— readiness  and  convenience  of  reference  being  the 
chief  aim. 

It  should,  perhaps,  be  said  here  that  the  various  chap- 
ters composing  this  book — like  those  of  "  Astronomy  with 
an  Opera-glass  "•  —were,  in  their  original  form,  with  the 
single  exception  of  Chapter  IX,  published  in  Appletons' 
Popular  Science  Monthly.  The  author,  it  is  needless  to  say, 
was  much  gratified  by  the  expressed  wish  of  many  readers 
that  these  scattered  papers  should  be  revised  and  collected 
in  a  more  permanent  form.  As  bearing  upon  the  general 
subject  of  the  book,  a  chapter  has  been  added,  at  the  end, 
treating  on  the  question  of  the  existence  of  planets  among 
the  stars.  This  also  first  appeared  in  the  periodical  above 
mentioned. 

In  conclusion,  the  author  wishes  for  his  readers  as 
great  a  pleasure  in  the  use  of  the  telescope  as  he  himself 
has  enjoyed.  GPS 

BOROUGH  OF  BROOKLYN,  NEW  YORK,  January,  1901. 


CONTENTS 


CHAPTER  I 

PAGE 

THE  SELECTION  AND  TESTING  OF  A  GLASS 1 

How  to  get  a  good  telescope — Difference  between  reflectors  and 
refractors — How  a  telescope  is  made  achromatic— The  way  to  test  a 
telescope  on  stars. 

CHAPTER  II 
IN  THE  STARRY  HEAVENS. 19 

Orion  and  its  wonders,  Lepus,  Canis  Major,  Argo,  Monoceros, 
Canis  Minor,  and  the  Head  of  Hydra. 

CHAPTER  III 

FROM  GEMINI  TO  LEO  AND  ROUND  ABOUT 38 

The  zodiacal  constellations  Gemini,  Cancer,  and  Leo,  and  their 
neighbors  Auriga,  the  Lynx,  Hydra,  Sextans,  and  Coma  Berenices. 

CHAPTER  IV 
VIRGO  AND  HER  NEIGHBORS 57 

Crater  and  Corvus,  Hydra,  Virgo,  the  "Field  of  the  Nebulae," 
Libra,  Bootes,  and  the  great  Arcturus,  Canes  Venatici,  and  Corona 
Borealis. 

CHAPTER  V 
IN  SUMMER  STAR-LANDS 75 

Scorpio  and  its  red-green  gem.  Ophiuchus,  Sagittarius,  Scutum 
Sobieskii,  Capricornus,  Serpens,  Hercules,  Draco,  Aquila,  and  Delphinus. 

CHAPTER  VI 
FROM  LYRA  TO  ERIDANUS v  ...       .       .97 

Lyra  and  its  brilliant  Vega,  Cygnus,  Vulpecula,  Aquarius,  Equuleus, 
Pegasus,  Cetus,  and  Eridanus. 

vii 


viii  PLEASURES  OF  THE  TELESCOPE 

CHAPTER  VII 

PAGE 

PISCES,  ARIES,  TAURUS,  AND  THE  NORTHERN  MARS  ....    117 

The  first  double  star  ever  discovered,  the  Pleiades  and  their  photo- 
graphic wonders,  the  Royal  Family  of  the  Sky,  Andromeda,  Cassiopeia, 
Perseus  and  Cepheus,  Ursa  Major,  Camelopardalus,  Ursa  Minor,  and  the 
Pole  Star. 

CHAPTER  VIII 
SCENES  ON  THE  PLANETS 139 

Jupiter,  its  belts  and  its  moons — Saturn,  the  ringed  planet — Saturn's 
moons  and  Roche's  limit — Mars  and  its  white  polar  caps  and  so-called 
seas  and  continents — Venus  and  her  atmosphere — The  peculiar  rota- 
tions of  Venus  and  Mercury. 

CHAPTER  IX 

THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON  AND  THE  SPECTACLES 

OF  THE  SUN 156 

Peculiarities  of  the  lunar  landscapes — The  sVcalled  seas,  the  craters, 
the  ring  mountains,  the  inclosed  plains,  the  mountain  ranges,  Tycho's 
mysterious  streaks,  and  other  lunar  features  described — How  to  view 
the  sun  and  its  spots. 

CHAPTER  X 

ARE  THERE  PLANETS  AMONG  THE  STARS  ? 183 

Significance  of  Dr.  See's  observations — Why  our  telescopes  do  not 
show  planets  circling  around  distant  suns — Reasons  for  thinking  that 
such  planets  may  exist — The  bearing  of  stellar  evolution  on  the  ques- 
tion. 


PLEASURES    OP   THE   TELESCOPE 


CHAPTER    I 

THE    SELECTION   AND   TESTING   OF   A   GLASS 

"O  telescope,  instrument  of  much  knowledge,  more  precious  than  any  scep- 
ter! Is  not  he  who  holds  thee  in  his  hand  made  king  and  lord  of  the  works  of 
God  ?  " — JOHN  KEPLER. 

IF  the  pure  and  elevated  pleasure  to  be  derived  from 
the  possession  and  use  of  a  good  telescope  of  three,  four, 
five,  or  six  inches  aperture  were  generally  known,  I  am 
certain  that  no  instrument  of  science  would  be  more  com- 
monly found  in  the  homes  of  intelligent  people.  The 
writer,  when  a  boy,  discovered  unexpected  powers  in  a 
pocket  telescope  not  more  than  fourteen  inches  long  when 
extended,  and  magnifying  ten  or  twelve  times.  It  became 
his  dream,  which  was  afterward  realized,  to  possess  a 
more  powerful  telescope,  a  real  astronomical  glass,  with 
which  he  could  see  the  beauties  of  the  double  stars,  the 
craters  of  the  moon,  the  spots  on  the  sun,  the  belts  and 
satellites  of  Jupiter,  the  rings  .of  Saturn,  the  extraor- 
dinary shapes  of  the  nebula,  the  crowds  of  stars  in  the 
Milky  Way,  and  the  great  stellar  clusters.  And  now  he 
would  do  what  he  can  to  persuade  others,  who  perhaps 
are  not  aware  how  near  at  hand  it  lies,  to  look  for  them- 
selves into  the  wonder-world  of  the  astronomers. 

There  is  only  one  way  in  which  you  can  be  sure  of 
getting  a  good  telescope.  First,  decide  how  large  a  glass 
you  are  to  have,  then  go  to  a  maker  of  established  reputa- 


2  PLEASURES  OF  THE  TELESCOPE 

tion,  fix  upon  the  price  you  are  willing  to  pay — remem- 
bering that  good  work  is  never  cheap — and  finally  see 
that  the  instrument  furnished  to  you  answers  the  proper 
tests  for  a  telescope  of  its  size.  There  are  telescopes  and 
telescopes.  Occasionally  a  rare  combination  of  perfect 
homogeneity  in  the  material,  complete  harmony  between 
the  two  kinds  of  glass  of  which  the  objective  is  composed, 
and  lens  surfaces  whose  curves  are  absolutely  right,  pro- 
duces a  telescope  whose  owner  would  part  with  his  last 
dollar  sooner  than  with  it.  Such  treasures  of  the  lens- 
maker's  art  can  not,  perhaps,  be  commanded  at  will,  yet, 
they  are  turned  out  with  increasing  frequency,  and  the 
best  artists  are  generally  able,  at  all  times,  to  approxi- 
mate so  closely  to  perfection  that  any  shortcoming  may 
be  disregarded. 

In  what  is  said  above  I  refer,  of  course,  to  the  refract- 
ing telescope,  which  is  the  form  of  instrument  that  I 
should  recommend  to  all  amateurs  in  preference  to  the 
reflector.  But,  before  proceeding  further,  it  may  be  well 
to  recall  briefly  the  principal  points  of  difference  between 
these  two  kinds  of  telescopes.  The  purpose  of  a  telescope 
of  either  description  is,  first,  to  form  an  image  of  the 
object  looked  at  by  concentrating  at  a  focus  the  rays  of 
light  proceeding  from  that  object.  The  refractor  achieves 
this  by  means  of  a  carefully  shaped  lens,  called  the  object 
glass,  or  objective.  The  reflector,  on  the  other  hand, 
forms  the  image  at  the  focus  of  a  concave  mirror. 

A  very  pretty  little  experiment,  which  illustrates  these 
two  methods  of  forming  an  optical  image,  and,  by  way  of 
corollary,  exemplifies  the  essential  difference  between  re- 
fracting and  reflecting  telescopes,  may  be  performed  by 
any  one  who  possesses  a  reading  glass  and  a  magnifying 
hand  mirror.  In  a  room  that  is  not  too  brightly  illumi- 
nated pin  a  sheet  of  white  paper  on  the  wall  opposite  to  a 


THE  SELECTION  AND   TESTING  OF  A    GLASS  3 

window  that,  by  preference,  should  face  the  north,  or 
away  from  the  position  of  the  sun.  Taking  first  the  read- 
ing glass,  hold  it  between  the  window  and  the  wall  paral- 


IMAGE  AT  THE  Focus  OF  A  LENS. 

lei  to  the  sheet  of  paper,  and  a  foot  or  more  distant  from 
the  latter.  By  moving  it  to  and  fro  a  little  you  wil  be  able 
to  find  a  distance,  corresponding  to  the  focal  length  of  the 
lens,  at  which  a  picture  of  the  window  is  formed  on  the 
paper.  This  picture,  or  image,  will  be  upside  down,  be- 
cause the  rays  of  light  cross  at  the  focus.  By  moving  the 
glass  a  little  closer  to  the  wall  you  will  cause  the  picture 


4  PLEASURES  OF  THE  TELESCOPE 

of  the  window  to  become  indistinct,  while  a  beautiful  im- 
age of  the  houses,  trees,  or  other  objects  of  the  outdoor 
world  beyond,  will  be  formed  upon  the  paper.  We  thus 
learn  that  the  distance  of  the  image  'from  the  lens  varies 
with  the  distance  of  the  object  whose  image  is  formed. 
In  precisely  a  similar  manner  an  image  is  formed  at  the 
focus  of  the  object  glass  of  a  refracting  telescope. 


IMAGE  AT  THE  Focus  OF  A  CONCAVE  MIRROR. 


Take  next  your  magnifying  or  concave  mirror,  and 
detaching  the  sheet  of  paper  from  the  wall,  hold  it  nearly 
in  front  of  the  mirror  between  the  latter  and  the  window. 


THE  SELECTION  AND   TESTING   OF  A   GLASS  5 

When  you  have  adjusted  the  distance  to  the  focal  length 
of  the  mirror,  you  will  see  an  image  of  the  window  pro- 
jected upon  the  paper,  and  by  varying  the  distance,  as 
before,  you  will  be  able  to  produce,  at  will,  pictures  of 
nearer  or  more  remote  objects.  It  is  in  this  way  that 
images  are  formed  at  the  focus  of  the  mirror  of  a  reflect- 
ing telescope. 

Now,  you  wrill  have  observed  that  the  chief  apparent 
difference  between  these  two  methods  of  forming  an  im- 
age of  distant  objects  is  that  in  the  first  case  the  rays  of 
light,  passing  through  the  transparent  lens,  are  brought 
to  a  focus  on  the  side  opposite  to  that  where  the  real 
object  is,  while  in  the  second  case  the  rays,  being  reflected 
from  the  brilliant  surface  of  the  opaque  mirror,  come 
to  a  focus  on  the  same  side  as  that  on  which  the  object 
itself  is.  From  this  follows  the  most  striking  difference 
in  the  method  of  using  refracting  and  reflecting  tele- 
scopes. In  the  refractor  the  observer  looks  toward  the 
object;  in  the  reflector  he  looks  away  from  it.  Sir  Wil- 
liam Herschel  made  his  great  discoveries  with  his  back  to 
the  sky.  He  used  reflecting  telescopes.  This  principle, 
again,  can  be  readily  illustrated  by  means  of  our  simple 
experiment  with  a  reading  glass  and  a  magnifying  mirror. 
Hold  the  reading  glass  between  the  eye  and  a  distant 
object  with  one  hand,  and  with  the  other  hand  place  a 
smaller  lens  such  as  a  pocket  magnifier,  near  the  eye,  and 
in  line  with  the  reading  glass.  Move  the  two  carefully 
until  they  are  at  a  distance  apart  equal  to  the  sum  of  the 
focal  lengths  of  the  lenses,  and  you  will  see  a  magnified 
image  of  the  distant  object.  In  other  words,  you  have 
constructed  a  simple  refracting  telescope.  Then  take  the 
magnifying  mirror,  and,  turning  your  back  to  the  object 
to  be  looked  at,  use  the  small  lens  as  before — that  is  to 
say,  hold  it-  between  your  eye  and  the  mirror,  so  that  its 


6  PLEASURES  OF  THE  TELESCOPE 

distance  from  the  latter  is  equal  to  the  sum  of  the  focal 
lengths  of  the  mirror  and  the  lens,  and  you  will  see  again 
a  magnified  image  of  the  distant  object.  This  time  it  is 
a  reflecting  telescope  that  you  hold  in  your  hands. 

The  magnification  of  the  image  reminds  us  of  the 
second  purpose  which  is  subserved  by  a  telescope.  A 
telescope,  whether*  refracting  or  reflecting,  consists  of 
two  essential  parts,  the  first  being  a  lens,  or  a  mirror,  to 
form  an  image,  and  the  second  a  microscope,  called  an 
eyepiece,  to  magnify  the  image.  The  same  eyepieces  will 
serve  for  either  the  reflector  or  the  refractor.  But  in 
order  that  the  magnification  may  be  effective,  and  serve 
to  reveal  what  could  not  be  seen  without  it,  the  image 
itself  must  be  as  nearly  perfect  as  possible;  this  requires 
that  every  ray  of  light  that  forms  the  image  shall  be 
brought  to  a  point  in  the  image  precisely  corresponding 
to  that  from  which  it  emanates  in  the  real  object.  In 
reflectors  this  is  effected  by  giving  a  parabolic  form  to 
the  concave  surface  of  the  mirror.  In  refractors  there  is 
a  twofold  difficulty  to  be  overcome.  In  the  first  place,  a 
lens  with  spherical  surfaces  does  not  bend  all  the  rays 
that  pass  through  it  to  a  focus  at  precisely  the  same  dis- 
tance. The  rays  that  pass  near  the  outer  edge  of  the 
lens  have  a  shorter  focus  than  that  of  the  rays  which  pass 
near  the  center  of  the  lens;  this  is  called  spherical  aberra- 
tion. A  similar  phenomenon  occurs  with  a  concave  mir- 
ror whose  surface  is  spherical.  In  that  case,  as  we  have 
seen,  the  difficulty  is  overcome  by  giving  the  mirror  a 
parabolic  instead  of  a  spherical  form.  In  an  analogous 
way  the  spherical  aberration  of  a  lens  can  be  corrected 
by  altering  its  curves,  but  the  second  difficulty  that  arises 
with  a  lens  is  not  so  easily  disposed  of:  this  is  what  is 
called  chromatic  aberration.  It  is  due  to  the  fact  that 
the  rays  belonging  to  different  parts  of  the  spectrum  have 


TEE  SELECTION  AND   TESTING   OF  A   GLASS  7 

different  degrees  of  refrangibility,  or,  in  other  words,  that 
they  come  to  a  focus  at  different  distances  from  the  lens; 
and  this  is  independent  of  the  form  of  the  lens.  The  blue 
rays  come  to  a  focus  first,  then  the  yellow,  and  finally  the 
red.  It  results  from  this  scattering  of  the  spectral  rays 
along  the  axis  of  the  lens  that  there  is  no  single  and  exact 
focus  where  all  meet,  and  that  the  image  of  a  star,  for 
instance,  formed  by  an  ordinary  lens,  even  if  the  spherical 
aberration  has  been  corrected,  appears  blurred  and  dis- 
colored. There  is  no  such  difficulty  with  a  mirror,  be- 
cause there  is  in  that  case  no  refraction  of  the  light,  and 
consequently  no  splitting  up  of  the  elements  of  the  spec- 
trum. 

In  order  to  get  around  the  obstacle  formed  by  chro- 
matic aberration  it  is  necessary  to  make  the  object  glass 
of  a  refractor  consist  of  two  lenses,  each  composed  of  a 
different  kind  of  glass.  One  of  the  most  interesting  facts 
in  the  history  of  the  telescope  is  that  Sir  Isaac  Newton 
could  see  no  hope  that  chromatic  aberration  would  be 
overcome,  and  accordingly  turned  his  attention  to  the 
improvement  of  the  reflecting  telescope  and  devised  a 
form  of  that  instrument  which  still  goes  under  his  name. 
And  even  after  Chester  More  Hall  in  1729,  and  John  Dol- 
lond  in  1757,  had  shown  that  chromatic  aberration  could 
be  nearly  eliminated  by  the  combination  of  a  flint-glass 
lens  with  one  of  crown  glass,  William  Herschel,  who 
began  his  observations  in  1774,  devoted  his  skill  entirely 
to  the  making  of  reflectors,  seeing  no  prospect  of  much 
advance  in  the  power  of  refractors. 

A  refracting  telescope  which  has  been  freed  from  the 
effects  of  chromatic  aberration  is  called  achromatic.  The 
principle  upon  which  its  construction  depends  is  that  by 
combining  lenses  of  different  dispersive  power  the  separa- 
tion of  the  spectral  colors  in  the  image  can  be  corrected 


8 


PLEASURES  OF  THE  TELESCOPE 


ACHROMATIC  OBJECT  GLASS. 
a,  crown  glass ;  6,  fliat  glass. 


while  the  convergence  of  the  rays  of  light  toward  a  focus 
is  not  destroyed.  Flint  glass  effects  a  greater  dispersion 
than  crown  glass  nearly  in  the  ratio  of  three  to  two. 

The  chromatic  combination 
consists  of  a  convex  lens 
of  crown  backed  by  a  con- 
cave, or  plano-concave,  lens 
of  flint.  When  these  two 
lenses  are  made  of  focal 
lengths  which  are  directly 
proportional  to  their  dis- 
persions, they  give  a  prac- 
tically colorless  image  at 
their  common  focus.  The 
skill  of  the  telescope-maker 
and  the  excellence  of  his  work  depend  upon  the  selection 
of  the  glasses  to  be  combined  and  his  manipulation  of  the 
curves  of  the  lenses. 

Now,  the  reader  may  ask,  "  Since  reflectors  require  no 
correction  for  color  dispersion,  while  that  correction  is 
only  approximately  effected  by  the  combination  of  two 
kinds  of  lenses  and  two  kinds  of  glass  in  a  refractor,  why 
is  not  the  reflector  preferable  to  the  refractor?  " 

The  answer  is,  that  the  refractor  gives  more  light  and 
better  definition.  It  is  superior  in  the  first  respect  be- 
cause a  lens  transmits  more  light  than  a  mirror  reflects. 
Professor  Young  has  remarked  that  about  eighty-two  per 
cent  of  the  light  reaches  the  eye  in  a  good  refractor,  while 
"  in  a  Newtonian  reflector,  in  average  condition,  the  per- 
centage seldom  exceeds  fifty  per  cent,  and  more  frequently 
is  lower  than  higher."  The  superiority  of  the  refractor  in 
regard  to  definition  arises  from  the  fact  that  any  dis- 
tortion at  the  surface  of  a  mirror  affects  the  direction  of 
a  ray  of  light  three  times  as  much  as  the  same  distortion 


THE  SELECTION  AND   TESTING   OF  A    GLASS  9 

would  do  at  the  surface  of  a  lens.  And  this  applies 
equally  both  to  permanent  errors  of  curvature  and  to  tem- 
porary distortions  produced  by  strains  and  by  inequality 
of  temperature.  The  perfect  achromatism  of  a  reflector 
is,  of  course,  a  great  advantage,  but  the  chromatic  aber- 
ration of  refractors  is  now  so  well  corrected  that  their 
inferiority  in  that  respect  may  be  disregarded.  It  must 
be  admitted  that  reflectors  are  cheaper  and  easier  to 
make,  but,  on  the  other  hand,  they  require  more  care,  and 
their  mirrors  frequently  need  resilvering,  while  an  object 
glass  with  reasonable  care  never  gets  seriously  out  of 
order,  and  will  last  for  many  a  lifetime. 

Enough  has  now,  perhaps,  been  said  about  the  respec- 
tive properties  of  object  glasses  and  mirrors,  but  a  word 
should  be  added  concerning  eyepieces.  Without  a  good 
eyepiece  the  best  telescope  will  not  perform  well.  The 
simplest  of  all  eyepieces  is  a  single  double-convex  lens. 
With  such  a  lens  the  magnifying  power  of  the  telescope 
is  measured  by  the  ratio  of  the  focal  length  of  the  objec- 
tive to  that  of  the  eye  lens.  Suppose  the  first  is  sixty 
inches  and  the  latter  half  an  inch;  then  the  magnifying 
power  will  be  a  hundred  and  twenty  diameters — i.  e.,  the 
disk  of  a  planet,  for  instance,  will  be  enlarged  a  hundred 
and  twenty  times  along  each  diameter,  and  its  area  will 
be  enlarged  the  square  of  a  hundred  and  twenty,  or  four- 
teen thousand  four  hundred  times.  But  in  reckoning 
magnifying  power,  diameter,  not  area,  is  always  consid- 
ered. For  practical  use  an  eyepiece  composed  of  an  ordi- 
nary single  lens  is  seldom  advantageous,  because  good 
definition  can  only  be  obtained  in  the  center  of  the  field. 
Lenses  made  according  to  special  formula?,  however,  and 
called  solid  eyepieces,  give  excellent  results,  and  for  high 
powers  are  often  to  be  preferred  to  any  other.  The  eye- 
pieces usually  furnished  with  telescopes  are,  in  their 


10 


PLEASURES  OF  THE  TELESCOPE 


essential  principles,  compound  microscopes,  and  they  are 
of  two  descriptions,  "  positive  "  and  "  negative."  The  for- 
mer generally  goes  under  the  name  of  its  inventor,  Hams- 
den,  and  the  latter  is  name'd  'after  the  great  Dutch  astron- 
omer, Huygens.  The  Huygens  eyepiece  consists  of  two 


NEGATIVE  EYEPIECE. 


POSITIVE  EYEPIECE. 


plano-convex  lenses  whose  focal  lengths  are  in  the  ratio 
of  three  to  one.  The  smaller  lens  is  placed  next  to  the 
eye.  Both  lenses  have  their  convex  surfaces  toward  the 
object  glass,  and  their  distance  apart  is  equal  to  half  the 
sum  of  their  focal  lengths.  In  this  kind  of  eyepiece  the 
image  is  formed  between  the  two  lenses,  and  if  the  work 
is  properly  done  such  an  eyepiece  is  achromatic.  It  ,is 
therefore  generally  preferred  for  mere  seeing  purposes. 
In  the  Ramsden  eyepiece  two  plano-convex  lenses  are  also 
used,  but  they  are  of  equal  focal  length,  are  placed  at  a 
distance  apart  equal  to  two  thirds  of  the  focal  length  of 
either,  and  have  their  convex  sides  facing  one  another. 
With  such  an  eyepiece  the  image  viewed  is  beyond  the 
farther  or  field  lens  instead  of  between  the  two  lenses,  and 
as  this  fact  renders  it  easier  to  adjust  wires  or  lines  for 
measuring  purposes  in  the  focus  of  the  eyepiece,  the 
Ramsden  construction  is  used  when  a  micrometer  is  to 
be  employed.  In  order  to  ascertain  the  magnifying  power 
which  an  eyepiece  gives  when  applied  to  a  telescope  it 
is  necessary  to  know  the  equivalent,  or  combined,  focal 
length  of  the  two  lenses.  Two  simple  rules,  easily  re- 
membered, supply  the  means  of  ascertaining  this.  The 
equivalent  focal  length  of  a  negative  or  Huygens  eyepiece 


THE  SELECTION  AND   TESTING   OF  A    GLASS  H 

is  equal  to  half  the  focal  length  of  the  larger  or  field  lens. 
The  equivalent  focal  length  of  a  positive  or  Ramsden  eye- 
piece is  equal  to  three  fourths  of  the  focal  length  of  either 
of  the  lenses.  Having  ascertained  the  equivalent  focal 
length  of  the  eyepiece,  it  is  only  necessary  to  divide  it  into 
the  focal  length  of  the  object  glass  (or  mirror)  in  order  to 
know  the  magnifying  power  of  your  telescope  when  that 
particular  eyepiece  is  in  use. 

A  first-class  object  glass  (or  mirror)  will  bear  a  mag- 
nifying power  of  one  hundred  to  the  inch  of  aperture 
when  the  air  is  in  good  condition — that  is,  if  you  are  look- 
ing at  stars.  If  you  are  viewing  the  moon,  or  a  planet, 
better  results  will  always  be  obtained  with  lower  powers 
— say  fifty  to  the  inch  at  the  most.  And  under  ordinary 
atmospheric  conditions  a  power  of  from  fifty  to  seventy- 
five  to  the  inch  is  far  better  for  stars  than  a  higher  power. 
With  a  five-inch  telescope  that  would  mean  from  two  hun- 
dred and  fifty  to  three  hundred  and  seventy-five  diame- 
ters, and  such  powers  should  only  be  applied  for  the  sake 
of  separating  very  close  double  stars.  As  a  general  rule, 
the  lowest  power  that  will  distinctly  show  what  you  de- 
sire to  see  gives  the  best  results.  The  experienced  ob- 
server never  uses  as  high  powers  as  the  beginner  does. 
The  number  of  eyepieces  purchased  with  a  telescope  should 
never  be  less  than  three — a  very  low  power — say  ten  to 
the  inch;  a  very  high  power,  seventy-five  or  one  hundred 
to  the  inch,  for  occasional  use;  and  a  medium  power — say 
forty  to  the  inch — for  general  use.  If  you  can  afford  it, 
get  a  full  battery  of  eyepieces — six  or  eight,  or  a  dozen— 
for  experience  shows  that  different  objects  require  differ- 
ent powers  in  order  to  be  best  seen,  and,  moreover,  a  slight 
change  of  power  is  frequently  a  great  relief  to  the  eye. 

There  is  one  other  thing  of  great  importance  to  be 
considered  in  purchasing  a  telescope — the  mounting.     If 


12  PLEASURES  OF  THE  TELESCOPE 

your  glass  is  not  well  mounted  on  a  steady  and  easily 
managed  stand,  you  might  better  have  spent  your  money 
for  something  more  useful.  I  have  endured  hours  of  tor- 
ment while  trying  to  see  stars  through  a  telescope  that 
was  shivering  in  the  wind  and  dancing  to  every  motion 
of  the  bystanders,  to  say  nothing  of  the  wriggling  contor- 
tions caused  by  the  application  of  my  own  fingers  to  the 
focusing  screw.  The  best  of  all  stands  is  a  solid  iron 
pillar  firmly  fastened  into  a  brick  or  stone  pier,  sunk  at 
least  four  feet  in  the  ground,  and  surmounted  by  a  well- 
made  equatorial  bearing  whose  polar  axis  has  been  care- 
fully placed  in  the  meridian.  It  can  be  readily  protected 
from  the  weather  by  means  of  a  wooden  hood  or  a  rubber 
sheet,  while  the  tube  of  the  telescope  may  be  kept  indoors, 
being  carried  out  and  placed  on  its  bearing  only  when  ob- 
servations are  to  be  made.  With  such  a  mounting  you 
can  laugh  at  the  observatories  with  their  cumbersome 
domes,  for  the  best  of  all  observatories  is  the  open  air. 
But  if  you  dislike  the  labor'of  carrying  and  adjusting  the 
tube  every  time  it  is  used,  and  are  both  fond  of  and  able 
to  procure  luxuries,  then,  after  all,  perhaps,  you  had 
better  have  the  observatory,  dome,  draughts  and  all. 

The  next  best  thing  in  the  way  of  a  mounting  is  a  port- 
able tripod  stand.  This  may  be  furnished  either  with 
an  equatorial  bearing  for  the  telescope,  or  an  altazimuth 
arrangement  which  permits  both  up-and-down  and  hori- 
zontal motions.  The  latter  is  cheaper  than  the  equatorial 
and  proportionately  inferior  in  usefulness  and  conven- 
ience. The  essential  principle  of  the  equatorial  bearing 
is  motion  about  two  axes  placed  at  right  angles  to  one 
another.  When  the  polar  axis  is  in  the  meridian,  and  in- 
clined at  an  angle  equal  to  the  latitude  of  the  place,  the 
telescope  can  be  moved  about  the  two  axes  in  such  a  way 
as  to  point  to  any  quarter  of  the  sky,  and  the  motion  of  a 


THE  SELECTION  AND   TESTING    OF  A    GLASS  13 

star,  arising  from  the  earth's  rotation,  can  be  followed 
hour  after  hour  without  disturbing  the  instrument. 
When  thus  mounted,  the  telescope  may  be  driven  by  clock- 
work, or  by  hand  with  the  aid  of  a  screw  geared  to  a 
handle  carrying  a  universal  joint. 

And  now  for  testing  the  telescope.  It  has  already 
been  remarked  that  the  excellence  of  a  telescope  depends 
upon  the  perfection  of  the  image  formed  at  the  focus  of 
the  objective.  In  what  follows  I  have  only  a  refractor  in 
mind,  although  the  same  principles  would  apply  to  a  re- 
flector. With  a  little  practice  anybody  who  has  a  correct 
eye  can  form  a  fair  judgment  of  the  excellence  of  a  tele- 
scopic image.  Suppose  we  have  our  telescope  steadily 
mounted  out  of  doors  (if  you  value  your  peace  of  mind  you 
will  not  try  to  use  a  telescope  pointed  out  of  a  window, 
especially  in  winter),  and  suppose  we  begin  our  observa- 
tions with  the  pole  star,  employing  a  magnifying  power  of 
sixty  or  seventy  to  the  inch.  Our  first  object  is  to  see  if 
the  optician  has  given  us  a  good  glass.  If  the  air  is  not 
reasonably  steady  we  had  better  postpone  our  experiment 
to  another  night,  because  we  shall  find  that  the  star  as 
seen  in  the  telescope  flickers  and  "  boils,"  and  behaves  in 
so  extraordinary  a  fashion  that  there  is  no  more  defini- 
tion in  the  image  than  there  is  steadiness  in  a  bluebottle 
buzzing  on  a  window  pane.  But  if  the  night  is  a  fine  one 
the  star  image  will  be  quiescent,  and  then  we  may  note  the 
following  particulars:  The  real  image  is  a  minute  bright 
disk,  about  one  second  of  arc  in  diameter  if  we  are  using  a 
four-and-a-half  or  five-inch  telescope,  and  surrounded  by 
one  very  thin  ring  of  light,  and  the  fragments,  so  to  speak, 
of  one  or  possibly  two  similar  rings  a  little  farther  from 
the  disk,  and  visible,  perhaps,  only  by  glimpses.  These 
"  diffraction  rings  "  arise  from  the  undulatory  nature  of 
light,  and  their  distance  apart  as  well  as  the  diameter  of 


14:  PLEASURES  OF  THE  TELESCOPE 

the  central  disk  depend  upon  the  length  of  the  waves  of 
light.  If  the  telescope  is  a  really  good  one,  and  both 
object  glass  and  eyepiece  are  properly  adjusted,  the  disk 
will  be  perfectly  round,  slightly  softer  at  the  edge,  but 
otherwise  equally  bright  throughout;  and  the  ring  or 
rings  surrounding  it  will  be  exactly  concentric,  and  not 
brighter  on  one  side  than  on  another.  Even  if  our  tele- 
scope were  only  two  inches  or  two  inches  and  a  half  in 
aperture  we  should  at  once  notice  a  little  bluish  star,  the 
mere  ghost  of  a  star  in  a  small  telescope,  hovering  near 
the  polar  star.  It  is  the  celebrated  "  companion,"  but  we 
shall  see  it  again  wnen  we  have  more  time  to  study  it. 
Now  let  us  put  the  star  out  of  focus  by  turning  the  focusing 
screw.  Suppose  we  turn  it  in  such  a  way  that  the  eyepiece 
moves  slightly  outside  the  focus,  or  away  from 
the  object  glass.  Very  beautiful  phenomena  im- 
mediately begin  to  make  their  appearance.  A 
slight  motion  outward  causes  the  little  disk 
to  expand  perceptibly,  and  just  as  this  expan- 
sion commences,  a  bright-red  point  appears  at  the  precise 
center  of  the  disk.  But,  the  outward  motion  continuing, 
this  red  center  disappears,  and  is  replaced  by  a  blue 
center,  which  gradually  expands  into  a  sort  of  flare 
over  the  middle  of  the  disk.  The  disk  itself  has  in 
the  mean  time  enlarged  into  a  series  of  concentric  bright 
rings,  graduated  in  luminosity  with  beautiful  precision 
from  center  toward  circumference.  The  outermost  ring 
is  considerably  brighter,  however,  than  it  would  be  if 
the  same  gradation  applied  to  it  as  applies  to  the  inner 
rings,  and  it  is  surrounded,  moreover,  on  its  outer  edge 
by  a  slight  flare  which  tends  to  increase  its  apparent 
width.  Next  let  us  return  to  the  focus  and  then  move 
the  eyepiece  gradually  inside  the  focal  point  or  plane. 
Once  more  the  star  disk  expands  into  a  series  of  circles, 


THE  SELECTION  AND   TESTING     OF  A    GLASS  15 

and,  if  we  except  the  color  phenomena  noticed  outside  the 
focus,  these  circles  are  precisely  like  those  seen  before  in 
arrangement,  in  size,  and  in  brightness.  If  they  were  not 
the  same,  we  should  pronounce  the  telescope  to  be  im- 
perfect. There  is  one  other  difference,  however,  besides 
the  absence  of  the  blue  central  flare,  and  that  is  a  faint 
reddish  edging  around  the  outer  ring  when  the  expansion 
inside  the  focus  is  not  carried  very  far.  Upon  continuing 
to  move  the  eyepiece  inside  or  outside  the  focus  we  ob- 
serve that  the  system  of  rings  becomes  larger,  while  the 
rings  themselves  rapidly  increase  in  number,  becoming  at 
the  same  time  individually  thinner  and  fainter. 

By  studying  the  appearance  of  the  star  disk  when  in 
focus  and  of  the  rings  when  out  of  focus  on  either  side,  an 
experienced  eye  can  readily  detect  any  fault  that  a  tele- 
scope may  have.  The  amateur,  of  course,  can  only  learn 
to  do  this  by  considerable  practice.  Any  glaring  and  seri- 
ous fault,  however,  will  easily  make  itself  manifest.  Sup- 
pose, for  example,  we  observe  that  the  image  of  a  star 
instead  of  being  perfectly  round  is  oblong,  and  that  a  simi- 
lar defect  appears  in  the  form  of  the  rings  when  the  eye- 
piece is  put  out  of  focus.  We  know  at  once  that  some- 
thing is  wrong;  but  the  trouble  may  lie  either  in  the  ob- 
ject glass,  in  the  eyepiece,  in  the  eye  of  the  observer  him- 
self, or  in  the  adjustment  of  the  lenses  in  the  tube.  A 
careful  examination  of  the  image  and  the  out-of-focus 
circles  will  enable  us  to  determine  with  which  of  these 
sources  of  error  we  have  to  deal.  If  the  star  image  when 
in  focus  has  a  sort  of  wing  on  one  side,  and  if  the  rings 
out  of  focus  expand  eccentrically,  appearing  wider  and 
larger  on  one  side  than  on  the  other,  being  at  the  same 
time  brightest  on  the  least  expanded  side,  then  the  object 
glass  is  probably  not  at  right  angles  to  the  axis  of  the 
tube  and  requires  readjustment.  That  part  of  the  object 


16  PLEASURES  OF  THE  TELESCOPE 

glass  on  the  side  where  the  rings  appear  most  expanded 
and  faintest  needs  to  be  pushed  slightly  inward.  This 
can  be  effected  by  means  of  counterscrews  placed  for  that 
purpose  in  or  around  the  cell.  But  if,  after  we  have  got 
the  object  glass  properly  squared  to  the  axis  of  the  tube 
or  the  line  of  sight,  the  image  and  the  ring  system  in  and 
out  of  focus  still  appear  oblong,  the  fault  of  astigmatism 
must  exist  either  in  the  objective,  the  eyepiece,  or  the 
eye.  The  chances  are  very  great  that  it  is  the  eye  itself 
that  is  at  fault.  We  may  be  certain  of  this  if  we  find,  on 
turning  the  head  so  as  to  look  into  the  telescope  with 
the  eye  in  different  positions,  that  the  oblong  image  turns 
with  the  head  of  the  observer,  keeping  its  major  axis  con- 
tinually in  the  same  relative  position  with  respect  to  the 
eye.  The  remedy  then  is  to  consult  an  oculist  and  get  a 
pair  of  cylindrical  eyeglasses.  If  the  oblong  image  does 
not  turn  round  with  the  eye,  but  does  turn  when  the  eye- 
piece is  twisted  round,  then  the  astigmatism  is  in  the  lat- 
ter. If,  finally,  it  does  not  follow  either  the  eye  or  the 
eyepiece,  it  is  the  objective  that  is  at  fault. 

But  instead  of  being  oblong,  the  image  and  the  rings 
may  be  misshapen  in  some  other  way.  If  they  are  three- 
cornered,  it  is  probable  that  the  object  glass  is  subjected 
to  undue  pressure  in  its  cell.  This,  if  the  telescope  has 
been  brought  out  on  a  cool  night  from  a  warm  room,  may 
arise  from  the  unequal  contraction  of  the  metal  work  and 
the  glass  as  they  cool  off.  In  fact,  no  good  star  image 
can  be  got  while  a  telescope  is  assuming  the  temperature 
of  the  surrounding  atmosphere.  Even  the  air  inclosed  in 
the  tube  is  capable  of  making  much  trouble  until  its  tem- 
perature has  sunk  to  the  level  of  that  outside.  Half  an 
hour  at  least  is  required  for  a  telescope  to  adjust  itself  to 
out-of-door  temperature,  except  in  the  summer  time,  and 
it  is  better  to  allow  an  hour  or  two  for  such  adjustment  in 


THE  SELECTION  AND    TESTING   OF  A    GLASS 


17 


cold  weather.  Any  irregularity  in  the  shape  of  the  rings 
which  persists  after  the  lenses  have  been  accurately  ad- 
justed and  the  telescope  has  properly  cooled  may  be  as- 
cribed to  imperfections,  such  as  veins  or  spots  of  unequal 
density  in  the  glass  forming  the 
objective. 

The  spherical  aberration  of 
an  object  glass  may  be  under- 
corrected  or  overcorrected.  In 
the  former  case  the  central  rings 
inside  the  focus  will  appear  faint 

and  the  outer  ones  unduly  strong,  while  outside  the  focus 
the  central  rings  will  be  too  bright  and  the  outer  ones  too 
feeble.  But  if  the  aberration  is  overcorrected  the  central 
rings  will  be  overbright  inside  the  focus  and  abnormally 
faint  outside  the  focus. 

Assuming  that  we  have  a  telescope  in  which  no  ob- 
vious fault  is  discernible,  the  next  thing  is  to  test  its  pow- 


123 
THE  OuT-OF-Focus  RINGS. 
1,  Correct  figure ;   2  and  3,  spher- 
ical aberration. 


Two  VIEWS  OF  MARS  IN 
The  smaller  with  a  three-and-three-eighths-inch  telescope ;  the  larger  with  a  nine-inch. 

ers  in  actual  work.  In  what  is  to  follow  I  shall  endeavor 
to  describe  some  of  the  principal  objects  in  the  heavens 
from  which  the  amateur  observer  may  expect  to  derive 
pleasure  and  instruction,  and  which  may  at  the  same  time 


18  PLEASURES  OF  THE  TELESCOPE 

serve  as  tests  of  the  excellence  of  his  telescope.  No  one 
should  be  deterred  or  discouraged  in  the  study  of  celes- 
tial objects  by  the  apparent  insignificance  of  his  means  of 
observation.  The  accompanying  pictures  of  the  planet 
Mars  may  serve  as  an  indication  of  the  fact  that  a  small 
telescope  is  frequently  capable  of  doing  work  that  ap- 
pears by  no  means  contemptible  when  placed  side  by  side 
with  that  of  the  greater  instruments  of  the  observatories. 


CHAPTER    II 

IN    THE    STARRY    HEAVENS 

"  Now  constellations,  Muse,  and  signs  rehearse; 
In  order  let  them  sparkle  in  thy  verse." — MANILIUS. 

LET  us  imagine  ourselves  the  happy  possessors  of 
three  properly  mounted  telescopes  of  five,  four,  and  three 
inches  aperture,  respectively.  A  fine  midwinter  evening 
has  come  along,  the  air  is  clear,  cool,  and  steady,  and  the 
heavens,  of  that  almost  invisible'  violet  which  is  reserved 
for  the  lovers  of  celestial  scenery,  are  spangled  with  stars 
that  hardly  twinkle.  We  need  not  disturb  our  minds 
about  a  few  thin  clouds  here  and  there  floating  lazily  in 
the  high  air;  they  announce  a  change  of  weather,  but 
they  will  not  trouble  us  to-night. 

Which  way  shall  we  look?  Our  eyes  will  answer  the 
question  for  us.  However  we  may  direct  them,  they  in- 
stinctively return  to  the  south,  and  are  lifted  to  behold 
Orion  in  his  glory,  now  near  the  meridian  and  midway  to 
the  zenith,  with  Taurus  shaking  the  glittering  Pleiades 
before  him,  and  Canis  Major  with  the  flaming  Dog  Star 
following  at  his  heels. 

Not  only  is  Orion  the  most  brilliant  of  all  constella- 
tions to  the  casual  star-gazer,  but  it  contains  the  richest 
mines  that  the  delver  for  telescopic  treasures  can  any- 
where discover.  We  could  not  have  made  a  better  begin- 
ning, for  here  within  a  space  of  a  few  square  degrees  we 
have  a  wonderful  variety  of  double  stars  and  multiple 

19 


20  PLEASURES  OF  THE  TELESCOPE 

stars,  so  close  and  delicate  as  to  test  the  powers  of  the 
best  telescopes,  besides  a  profusion  of  star-clusters  and 
nebulae,  including  one  of  the  supreme  marvels  of  space, 
the  Great  Nebula  in  the  Sword. 

Our  star  map  No.  1  will  serve  as  a  guide  to  the  objects 
which  we  are  about  to  inspect.  Let  us  begin  operations 
with  our  smallest  telescope,  the  three-inch.  I  may  re- 
mark here  that,  just  as  the  lowest  magnifying  power  that 
will  clearly  reveal  the  object  looked  for  gives  ordinarily 
better  results  than  a  higher  power,  so  the  smallest  tele- 
scope that  is  competent  to  show  what  one  wishes  to  see 
is  likely  to  yield  more  satisfaction,  as  far  as  that  particu- 
lar object  is  concerned,  than  a  larger  glass.  The  larger 
the  object  glass  and  the  higher  the  power,  the  greater  are 
the  atmospheric  difficulties.  A  small  telescope  will  per- 
form very  well  on  a  night  when  a  large  one  is  helpless. 

Turn  the  glass  upon  /3  (Rigel),  the  white  first-magni- 
tude star  in  Orion's  left  foot.  Observe  whether  the  image 
with  a  high  power  is  clear,  sharp,  and  free  from  irregular 
wisps  of  stray  light.  Look  at  the  rings  in  and  out  of 
focus,  and  if  you  are  satisfied  with  the  performance,  try 
for  the  companion.  A  good  three-inch  is  certain  to  show 
it,  except  in  a  bad  state  of  the  atmosphere,  and  even  then 
an  expert  can  see  it,  at  least  by  glimpses.  The  com- 
panion is  of  the  ninth  magnitude,  some  say  the  eighth, 
and  the  distance  is  about  9.5",  angle  of  position  (hereafter 
designated  by  p.)  199°.*  Its  color  is  blue,  in  decided  con- 

*  The  angle  of  position  measures  the  inclination  to  the  meridian  of  a  line 
drawn  between  the  principal  star  and  its  companion ;  in  other  words,  it  shows  in 
what  direction  from  the  primary  we  must  look  for  the  companion.  It  is  reckoned 
from  0°  up  to  360°,  beginning  at  the  north  point  and  passing  around  by  east 
through  south  and  west  to  north  again.  Thus,  if  the  angle  of  position  is  0°  or 
360°,  the  companion  is  on  the  north  side  of  the  primary;  if  the  angle  is  90°,  the 
companion  is  to  the  east;  if  180°,  to  the  south;  if  270°,  to  the  west,  and  so  for 
intermediate  angles.  It  must  be  remembered,  however,  that  in  the  field  of  the 
telescope  the  top  is  south  and  the  bottom  north,  unless  a  prism  is  used,  when 


MAP  No.  i. 


22  PLEASURES  OF  THE  TELESCOPE 

trast  with  the  white  light  of  its  great  primary.  Sir  John 
Herschel,  however,  saw  the  companion  red,  as  others  have 
done.  These  differences  are  doubtless  due  to  imperfec- 
tions of  the  eye  or  the  telescope/"  In  1871  Burnham  be- 
lieved he  had  discovered  that  the  companion  was  an  ex- 
ceedingly close  double  star.  No  one  except  Burnham 
himself  succeeded  in  dividing  it,  and  he  could  only  do  so 
at  times.  Afterward,  when  he  was  at  Mount  Hamilton, 
he  tried  in  vain  to  split  it  with  the  great  thirty-six-inch 
telescope,  in  1889,  1890,  and  1891.  His  want  of  success 
induced  him  to  suggest  that  the  component  stars  were  in 
rapid  motion,  and  so,  although  he  admitted  that  it  might 
not  be  double  after  all,  he  advised  that  it  should  be 
watched  for  a  few  years  longer.  His  confidence  was  justi- 
fied, for  in  1898  Aitken,  with  the  Lick  telescope,  saw  and 
measured  the  distance  of  the  extremely  minute  companion 
—distance  0.17",  p.  177°. 

Rigel  has  been  suspected  of  a  slight  degree  of  variabil- 
ity. It  is  evidently  a  star  of  enormous  actual  magnitude, 
for  its  parallax  escapes  trustworthy  measurement.  It 
can  only  be  ranked  among  the  very  first  of  the  light- 
givers  of  the  visible  universe.  Spectroscopically  it  be- 
longs to  a  peculiar  type  which  has  very  few  representa- 
tives among  the  bright  stars,  and  which  has  been  thus 
described:  "  Spectra  in  which  the  hydrogen  lines  and  the 
few  metallic  lines  all  appear  to  be  of  equal  breadth  and 
sharp  definition."  Rigel  shows  a  line  which  some  believe 
to  represent  magnesium;  but  while  it  has  iron  lines  in  its 
spectrum,  it  exhibits  no  evidence  of  the  existence  of  any 
such  cloud  of  volatilized  iron  as  that  which  helps  to  en- 
velop the  sun. 

directions  become  complicated.  East  and  west  can  be  readily  identified  by 
noticing  the  motion  of  a  star  through  the  field ;  it  moves  toward  the  west  and 
from  the  east. 


IN  THE  STARRY  HEAVENS  23 

For  another  test  of  what  the  three-inch  will  do  turn 
to  ?,  the  lower,  or  left-hand,  star  in  the  Belt.  This  is  a 
triple,  the  magnitudes  being  second,  sixth,  and  tenth. 
The  sixth-magnitude  star  is  about  2.5"  from  the  primary, 
p.  149°,  and  has  a  very  peculiar  color,  hard  to  describe. 
It  requires  careful  focusing  to  get  a  satisfactory  view  of 
this  star  with  a  three-inch  telescope.  Use  magnifying 
powers  up  to  two  hundred  and  fifty  diameters.  With  our 
four-inch  the  star  is  much  easier,  and  the  five-inch  showrs 
it  readily  with  a  power  of  one  hundred.  The  tenth-magni- 
tude companion  is  distant  56",  p.  8°,  and  may  be  glimpsed 
with  the  three-inch.  Upon  the  whole,  we  shall  find  that 
we  get  more  pleasing  views  of  f  Orionis  with  the  four- 
inch  glass. 

Just  to  the  left  of  f,  and  in  the  same  field  of  view  with 
a  very  low  power,  is  a  remarkable  nebula  bearing  the 
catalogue  number  1227.  We  must  use  our  five-inch  on 
this  with  a  low  power,  but  with  ?  out  of  the  field  in  order 
to  avoid  its  glare.  The  nebula  is  exceedingly  faint,  and 
we  can  be  satisfied  if  we  see  it  simply  as  a  hazy  spot, 
although  with  much  larger  telescopes  it  has  appeared  at 
least  half  a  degree  broad.  Tempel  saw  several  centers 
of  condensation  in  it,  and  traced  three  or  four  broad  nebu- 
lous streams,  one  of  which  decidedly  suggested  spiral 
motion. 

The  upper  star  in  the  Belt,  8,  is  double;  distance,  53", 
p.  360°;  magnitudes,  second  and  seventh  very  nearly; 
colors,  white  and  green  or  blue.  This,  of  course,  is  an 
easy  object  for  the  three-inch  with  a  low  magnifying 
power.  It  Would  be  useless  to  look  for  the  two  fainter 
companions  of  S,  discovered  by  Burnham,  even  with  our 
five-inch  glass.  But  we  shall  probably  need  the  five-inch 
for  our  next  attempt,  and  it  will  be  well  to  put  on  a  high 
power,  say  three  hundred  diameters.  The  star  to  be  ex- 


24  PLEASURES  OF  THE  TELESCOPE 

amined  is  the  little  brilliant  dangling  below  the  right- 
hand  end  of  the  Belt,  toward  Rigel.  It  appears  on  the 
map  as  TJ.  Spare  no  pains  in  getting  an  accurate  focus, 
for  here  is  something  worth  looking  at,  and  unless  you 
have  a  trained  eye  you  will  not  easily  see  it.  The  star  is 
double,  magnitudes  third  and  sixth,  and  the  distance  from 
center  to  center  barely  exceeds  1",  p.  87°.  A  little  tremu- 
lousness  of  the  atmosphere  for  a  moment  conceals  the 
smaller  star,  although  its  presence  is  manifest  from  the 
peculiar  jutting  of  light  on  one  side  of  the  image  of  the 
primary.  But  in  an  instant  the  disturbing  undulations 
pass,  the  air  steadies,  the  image  shrinks  and  sharpens, 
and  two  points  of  piercing  brightness,  almost  touch- 
ing one  another,  dart  into  sight,  the  more  brilliant  one 
being  surrounded  by  an  evanescent  circle,  a  tiny  ripple  of 
light,  which,  as  it  runs  round  the  star  and  then  recedes, 
alternately  embraces  and  releases  the  smaller  companion. 
The  wash  of  the  light-waves  in  the  atmosphere  provokes 
many  expressions  of  impatience  from  the  astronomer,  but 
it  is  often  a  beautiful  phenomenon  nevertheless. 

Between  rj  and  3  is  a  fifth-magnitude  double  star,  2  725, 
which  is  worth  a  moment's  attention.  The  primary,  of  a 
reddish  color,  has  a  very  faint  star,  eleventh  magnitude, 
at  a  distance  of  12.7",  p.  88°. 

Still  retaining  the  five-inch  in  use,  we  may  next  turn 
to  the  other  end  of  the  Belt,  where,  just  under  f,  we  per- 
ceive the  fourth-magnitude  star  o-.  He  must  be  a  person 
of  indifferent  mind  who,  after  looking  with  unassisted 
eyes  at  the  modest  glimmering  of  this  little  star,  can  see 
it  as  the  telescope  reveals  it  without  a  thrill  of  wonder 
and  a  cry  of  pleasure.  The  glass,  as  by  a  touch  of  magic, 
changes  it  from  one  into  eight  or  ten  stars.  There  are 
two  quadruple  sets  three  and  a  half  minutes  of  arc  apart. 
The  first  set  exhibits  a  variety  of  beautiful  colors.  The 


IN  THE  STARRY  HEAVENS  25 

largest  star,  of  fourth  magnitude,  is  pale  gray;  the  second 
in  rank,  seventh  magnitude,  distance  42",  p.  61°,  presents 
a  singular  red,  "grape-red"  Webb  calls  it;  the  third, 
eighth  magnitude,  distance  12",  p.  84°,  is  blue;  and  the 
fourth,  eleventh  magnitude,  distance  12",  p.  236°,  is  ap- 
parently white.  Burnham  has  doubled  the  fourth-mag- 
nitude star,  distance  0.23".  The  second  group  of  four 
stars  consists  of  three  of  the  eighth  to  ninth  magnitude, 
arranged  in  a  minute  triangle  with  a  much  fainter  star 
near  them.  Between  the  two  quadruple  sets  careful  gaz- 
ing reveals  two  other  very  faint  stars.  While  the  five- 
inch  gives  a  more  satisfactory  view  of  this  wonderful  mul- 
tiple star  than  any  smaller  telescope  can  do,  the  four-inch 
and  even  the  three-inch  would  have  shown  it  to  us  as  a 
very  beautiful  object.  However  we  look  at  them,  there 
is  an  appearance  of  association  among  these  stars,  shin- 
ing with  their  contrasted  colors  and  their  various  degrees 
of  brilliance,  which  is  significant  of  the  diversity  of  con- 
ditions and  circumstances  under  which  the  suns  and 
worlds  beyond  the  solar  walk  exist. 

From  <r  let  us  drop  down  to  see  the  wonders  of  Orion's 
Sword  displayed  just  beneath.  We  can  use  with  advan- 
tage any  one  of  our  three  telescopes;  but  since  we  are 
going  to  look  at  a  nebula,  it  is  fortunate  that  we  have  a 
glass  so  large  as  five  inches  aperture.  It  will  reveal  in- 
teresting things  that  escape  the  smaller  instruments,  be- 
cause it  grasps  more  than  one  and  a  half  times  as  much 
light  as  the  four-inch,  and  nearly  three  times  as  much  as 
the  three-inch;  and  in  dealing  with  nebula  a  plenty  of 
light  is  the  chief  thing  to  be  desired.  The  middle  star  in 
the  Sword  is  0,  and  is  surrounded  by  the  celebrated 
Nebula  of  Orion.  The  telescope  shows  0  separated  into 
four  stars  arranged  at  the  corners  of  an  irregular  square, 
and  shining  in  a  black  gap  in  the  nebula.  These  four 
3 


26  PLEASURES  OF  THE  TELESCOPE 

stars  are  collectively  named  the  Trapezium.  The  bright- 
est is  of  the  sixth  magnitude,  the  others  are  of  the 
seventh,  seven  and  a  half,  and  eighth  magnitudes  respec- 
tively. The  radiant  mist  about  them  has  a  faint  green- 
ish tinge,  while  the  four  stars,  together  with  three  others 
at  no  great  distance,  which  follow  a  fold  of  the  nebula 
like  a  row  of  buttons  on  a  coat,  always  appear  to  me  to 
show  an  extraordinary  liveliness  of  radiance,  as  if  the 
strange  haze  served  to  set  them  off. 

Our  three-inch  would  have  shown  the  four  stars  of  the 
Trapezium  perfectly  well,  and  the  four-inch  would  have 
revealed  a  fifth  star,  very  faint,  outside  a  line  joining  the 

smallest  of  the  four 
and  its  nearest  neigh- 
bor. But  the  five- 
inch  goes  a  step  far- 
ther and  enables  us,, 
with  steady  gazing  to 
see  even  a  sixth  star, 
of  only  the  twelfth 
magnitude,  just  out- 

THE  TRAPEZIUM  WITH  THE  FIFTH  AND  SIXTH  STARS.  ^ne      *  r^P^zlum> 

near     the     brightest 

member  of  the  quartet.  The  Lick  telescope  has  disclosed 
one  or  two  other  minute  points  of  light  associated  with 
the  Trapezium.  But  more  interesting  than  the  Trape- 
zium is  the  vast  cloud,  full  of  strange  shapes,  surrounding 
it.  Nowhere  else  in  the  heavens  is  the  architecture  of 
a  nebula  so  clearly  displayed.  It  is  an  unfinished  temple 
whose  gigantic  dimensions,  while  exalting  the  imagina- 
tion, proclaim  the  omnipotence  of  its  builder.  But 
though  unfinished  it  is  not  abandoned.  The  work  of  crea- 
tion is  proceeding  within  its  precincts.  There  are  stars 
apparently  completed,  shining  like  gems  just  dropped 


IN  THE  STAEBY  HEAVENS  27 

from  the  hand  of  the  polisher,  and  around  them  are 
masses,  eddies,  currents,  and  swirls  of  nebulous  matter 
yet  to  be  condensed,  compacted,  and  constructed  into 
suns.  It  is  an  education  in  the  nebular  theory  of  the 
universe  merely  to  look  at  this  spot  with  a  good  tele- 
scope. If  we  do  not  gaze  at  it  long  and  wistfully,  and 
return  to  it  many  times  with  unflagging  interest,  we  may 
be  certain  that  there  is  not  the  making  of  an  astronomer 
in  us. 

Before  quitting  the  Orion  nebula  do  not  fail  to  notice 
an  eighth-magnitude  star,  a  short  distance  northeast  of 
the  Great  Nebula,  and  nearly  opposite  the  broad  opening 
in  the  latter  that  leads  in  toward  the  gap  occupied  by  the 
Trapezium.  This  star  is  plainly  enveloped  in  nebulosity, 
that  is  unquestionably  connected  with  the  larger  mass  of 
which  it  appears  to  form  a  satellite. 

At  the  lower  end  of  the  Sword  is  the  star  *,  somewhat 
under  the  third  magnitude.  Our  three-inch  will  show 
that  it  has  a  bluish  companion  of  seventh  or  eighth  mag- 
nitude, at  a  little  more  than  11"  distance,  p.  142°,  and  the 
larger  apertures  will  reveal  a  third  star,  of  tenth  mag- 
nitude, and  reddish  in  color,  distance  49",  p.  103°.  Close 
by  i  we  find  the  little  double  star  2  747,  whose  compo- 
nents are  of  five  and  a  half  and  six  and  a  half  magnitudes 
respectively,  and  separated  36",  p.  223°.  Above  the  up- 
permost star  in  the  Sword  is  a  small  star  cluster,  No. 
1184,  which  derives  a  special  interest  from  the  fact  that  it 
incloses  a  delicate  double  star,  2  750,  whose  larger  com- 
ponent is  of  the  sixth  magnitude,  while  the  smaller  is  of 
the  ninth,  and  the  distance  is  only  4.3",  p.  59°.  We  may 
try  the  four-inch  on  this  object. 

Having  looked  at  a  (Betelgeuse),  the  great  topaz  star 
on  Orion's  right  shoulder,  and  admired  the  splendor  of  its 
color,  we  may  turn  the  four-inch  upon  the  star  2  795,  fre- 


28  PLEASURES  OF  THE  TELESCOPE 

quently  referred  to  by  its  number  as  "  52  Orionis."  It  con- 
sists of  one  star  of  the  sixth  and  another  of  sixth  and  a 
half  magnitude,  only  1.5"  apart,  p.  200°.  Having  sepa- 
rated them  with  a  power  of  two  hundred  and  fifty  diame- 
ters on  the  four-inch,  we  may  try  them  with  a  high  power 
on  the  three-inch.  We  shall  only  succeed  this  time  if 
our  glass  is  of  first-rate  quality  and  the  air  is  perfectly 
steady. 

The  star  X  in  Orion's  head  presents  an  easy  conquest 
for  the  three-inch,  as  it  consists  of  a  light-yellow  star  of 
magnitude  three  and  a  half  and  a  reddish  companion  of 
the  sixth  magnitude;  distance  4",  p.  43°.  There  is  also 
a  twelfth-magnitude  star  at  27",  p.  183°,  and  a  tenth  or 
eleventh  magnitude  one  at  149",  p.  278°.  These  are  tests 
for  the  five-inch,  and  we  must  not  be  disappointed  if  we 
do  not  succeed  in  seeing  the  smaller  one  even  with  that 
aperture. 

Other  objects  in  Orion,  to  be  found  with  the  aid  of 
our  map,  are:  2  627,  a  double  star,  magnitude  six  and  a 
half  and  seven,  distance  21",  p.  260°;  O  2  98,  otherwise 
named  i  Orionis,  double,  magnitude  six  and  seven,  distance 
1",  p.  180°,  requires  five-inch  glass;  2  652,  double,  magni- 
tudes six  and  a  half  and  eight,  distance  1.7",  p.  184°;  p, 
double,  magnitudes  five  and  eight  and  a  half,  the  latter 
blue,  distance  7",  p.  62°,  may  be  tried  with  a  three-inch;  T, 
triple  star,  magnitudes  four,  ten  and  a  half,  and  eleven, 
distances  36",  p.  249°,  and  36",  p.  60°.  Burnham  discov- 
ered that  the  ten-and-a-half  magnitude  star  is  again 
double,  distance  4",  p.  50°.  There  is  not  much  satisfac- 
tion in  attempting  T  Orionis  with  telescopes  of  ordinary 
apertures;  2  Osfr,  otherwise  m  Orionis,  double,  magnitudes 
five  and  a  half  (greenish)  and  seven,  distance  31.7",  p.  28°, 
a  pretty  object;  2  728,  otherwise  A  32,  double,  magnitudes 
five  and  seven,  distance,  0.5"  or  less,  p.  206°,  a  rapid 


IN  THE  STARRY  HEAVENS  29 

binary,*  which  is  at  present  too  close  for  ordinary  tele- 
scopes, although  it  was  once  within  their  reach;  2  729, 
double,  magnitudes  six  and  eight,  distance  2",  p.  26°,  the 
smaller  star  pale  blue — try  it  with  a  four-inch,  but  five- 
inch  is  better;  2  816,  double,  magnitudes  six  and  half  and 
eight  and  a  half,  distance  4",  p.  289°;  ^2,  double,  magni- 
tudes five  and  a  half  and  eleven,  distance  3",  or  a  little 
less,  p.  322°;  905,  star  cluster,  contains  about  twenty 
stars  from  the  eighth  to  the  eleventh  magnitude;  1267, 
nebula,  faint,  containing  a  triple  star  of  the  eighth  magni- 
tude, two  of  whose  components  are  51"  apart,  while  the 
third  is  only  1.7"  from  its  companion,  p.  85°;  1376,  star 
cluster,  small  and  crowded;  1361,  star  cluster,  triangular 
shape,  containing  thirty  stars,  seventh  to  tenth  magni- 
tudes, one  of  which  is  a  double,  distance  2.4". 

Let  us  now  leave  the  inviting  star-fields  of  Orion  and 
take  a  glance  at  the  little  constellation  of  Lepus,  crouch- 
ing at  the  feet  of  the  mythical  giant.  We  may  begin  with 
a  new  kind  of  object,  the  celebrated  red  variable  R  Le- 
poris  (map  No.  1).  This  star  varies  from  the  sixth  or 
seventh  magnitude  to  magnitude  eight  and  a  half  in  a 
period  of  four  hundred  and  twenty-four  days.  Hind's 
picturesque  description  of  its  color  has  frequently  been 
quoted.  He  said  it  is  "  of  the  most  intense  crimson,  re- 
sembling a  blood-drop  on  the  black  ground  of  the  sky." 
It  is  important  to  remember  that  this  star  is  reddest  when 
faintest,  so  that  if  we  chance  to  see  it  near  its  maximum  of 
brightness  it  will  not  impress  us  as  being  crimson  at  all, 
but  rather  a  dull,  coppery  red.  Its  spectrum  indicates 
that  it  is  smothered  with  absorbing  vapors,  a  sun  near 
extinction  which,  at  intervals,  experiences  an  accession  of 
energy  and  bursts  through  its  stifling  envelope  with  ex- 

*  The  term  "binary"  is  used  to  describe  double  stars  which  are  in  motion 
about  their  common  center  of  gravity. 


30  PLEASURES  OF  THE  TELESCOPE 

plosive  radiance,  only  to  faint  and  sink  once  more.  It  is 
well  to  use  our  largest  aperture  in  examining  this  star. 

We  may  also  employ  the.  five-inch  for  an  inspection  of 
the  double  star  i,  whose  chief  component  of  the  fifth  mag- 
nitude is  beautifully  tinged  with  green.  The  smaller 
companion  is  very  faint,  eleventh  magnitude,  and  the  dis- 
tance is  about  13",  p.  337°. 

Another  fine  double  in  Lepus  is  *,  to  be  found  just 
below  *;  the  components  are  of  the  fifth  and  eighth  mag- 
nitudes, pale  yellow  and  blue  respectively,  distance  2.5", 
p.  360°;  the  third-magnitude  star  a  has  a  tenth-magnitude 
companion  at  a  distance  of  35",  p.  156°,  and  its  neighbor  ft 
(map  No.  2),  according  to  Burnham,  is  attended'  by  three 
eleventh-magnitude  stars,  two  of  which  are  at  distances 
of  206",  p.  75°,  and  240",  p.  58°,  respectively,  while  the 
third  is  less  than  3"  from  0,  p.  288° ;  the  star  7  (map  No.  2) 
is  a  wide  double,  the  distance  being  94",  and  the  magni- 
tudes four  and  eight.  The  star  numbered  45  is  a  remark- 
able multiple,  but  the  components  are  too  faint  to  possess 
much  interest  for  those  who  are  not  armed  with  very  pow- 
erful telescopes. 

From  Lepus  we  pass  to  Canis  Major  (map  No.  2). 
There  is  no  hope  of  our  being  able  to  see  the  companion 
of  a  (Sirius),  at  present  (1901),  even  with  our  five-inch. 
Discovered  by  Alvan  Clark  with  an  eighteen-inch  tele- 
scope in  1862,  when  its  distance  was  10"  from  the  center 
of  Sirius,  this  ninth-magnitude  star  has  since  been  swal- 
lowed up  in  the  blaze  of  its  great  primary.  At  first,  it 
slightly  increased  its  distance,  and  from  1868  until  1879 
most  of  the  measures  made  by  different  observers  con- 
siderably exceeded  11".  Then  it  began  to  close  up,  and  in 
1890  the  distance  scarcely  exceeded  4".  Burnham  was 
the  last  to  catch  sight  of  it  with  the  Lick  telescope  in  that 
year.  After  that  no  human  eye  saw  it  until  1896,  when  it 


32  PLEASURES  OF  THE  TELESCOPE 

was  rediscovered  at  the  Lick  Observatory.  Since  then 
the  distance  has  gradually  increased  to  nearly  5".  Ac- 
cording to  Burnham,  its  periodic  time  is  about  fifty-three 
years,  and  its  nearest  approach  to  Sirius  should  have 
taken  place  in  the  middle  of  1892.  Later  calculations 
reduce  the  periodic  time  to  forty-eight  or  forty-nine  years. 
If  we  can  not  see  the  companion  of  the  Dog  Star  with  our 
instruments,  we  can  at  least,  while  admiring  the  splendor 
of  that  dazzling  orb,  reflect  with  profit  upon  the  fact  that 
although  the  companion  is  ten  thousand  times  less  bright 
than  Sirius,  it  is  half  as  massive  as  its  brilliant  neighbor. 
Imagine  a  subluminous  body  half  as  ponderous  as  the  sun 
to  be  set  revolving  round  it  somewhere  between  Uranus 
and  Neptune.  Remember  that  that  body  would  possess 
one  hundred  and  sixty-five  thousand  times  the  gravitating 
energy  of  the  earth,  and  that  five  hundred  and  twenty 
Jupiters  would  be  required  to  equal  its  power  of  attrac- 
tion, and  then  consider  the  consequences  to  our  easy-going 
planets!  Plainly  the  solar  system  is  not  cut  according  to 
the  Sirian  fashion.  We  shall  hardly  find  a  more  remark- 
able coupling  of  celestial  bodies  until  we  come,  on  another 
evening,  to  a  star  that  began,  ages  ago,  to  amaze  the 
thoughtful  and  inspire  the  superstitious  with  dread — the 
wonderful  Algol  in  Perseus. 

We  may  remark  in  passing  that  Sirius  is  the  brightest 
representative  of  the  great  spectroscopic  type  I,  which 
includes  more  than  half  of  all  the  stars  yet  studied,  and 
which  is  characterized  by  a  white  or  bluish-white  color, 
and  a  spectrum  possessing  few  or  at  best  faint  metallic 
lines,  but  remarkably  broad,  black,  and  intense  lines  of 
hydrogen.  The  inference  is  that  Sirius  is  surrounded  by 
an  enormous  atmosphere  of  hydrogen,  and  that  the  in- 
tensity of  its  radiation  is  greater,  surface  for  surface, 
than  that  of  the  sun.  There  is  historical  evidence  to  sup- 


/A^  THE  STARRY  HEAVENS  33 

port  the  assertion,  improbable  in  itself,  that  Sirius,  with- 
in eighteen  hundred  years,  has  changed  color  from  red 
to  white. 

With  either  of  our  telescopes  we  shall  have  a  feast  for 
the  eye  when  we  turn  the  glass  upon  the  star  cluster 
No.  1454,  some  four  degrees  south  of  Sirius.  Look  for  a 
red  star  near  the  center.  Observe  the  curving  rows  so 
suggestive  of  design,  or  rather  of  the  process  by  which 
this  cluster  was  evolved  out  of  a  pre-existing  nebula.  You 
will  recall  the  winding  streams  in  the  Great  Nebula  of 
Orion.  Another  star  cluster  worth  a  moment's  attention 
is  No.  1479,  above  and  to  the  left  of  Sirius.  We  had  bet- 
ter use  the  five-inch  for  this,  as  many  of  the  stars  are  very 
faint.  Not  far  away  we  find  the  double  star  p,  whose 
components  are  of  the  fifth  and  eighth  magnitudes,  dis- 
tance 2.8",  p.  343°.  The  small  star  is  pale  blue.  Cluster 
No.  1512  is  a  pleasing  object  with  our  largest  aperture. 
In  No.  1511  we  have  a  faint  nebula  remarkable  for  the 
rows  of  minute  stars  in  and  near  it.  The  star  7  is  an 
irregular  variable.  In  1670  it  is  said  to  have  almost  dis- 
appeared, while  at  the  beginning  of  the  eighteenth  cen- 
tury it  was  more  than  twice  as  bright  as  it  is  to-day.  The 
reddish  star  8  is  also  probably  variable.  In  my  "  Astron- 
omy with  an  Opera  Glass  "  will  be  found  a  cut  showing 
a  singular  array  of  small  stars  partly  encircling  S.  These 
are  widely  scattered  by  a  telescope,  even  with  the  lowest 
power. 

Eastward  from  Canis  Major  we  find  some  of  the  stars 
of  Argo  Navis.  2  1097,  of  the  sixth  magnitude,  has  two 
minute  companions  at  20"  distance,  p.  311°  and  312°. 
The  large  star  is  itself  double,  but  the  distance,  0.8", 
p.  166°,  places  it  beyond  our  reach.  According  to  Burn- 
ham,  there  is  yet  a  fourth  faint  star  at  31",  p.  40°.  Some 
three  degrees  and  a  half  below  and  to  the  left  of  the  star 


IN  THE  STARRY  HEAVENS  35 

just  examined  is  a  beautiful  star  cluster,  No.  1551.  Nos. 
1564,  1571,  and  1630  are  other  star  clusters  well  worth 
examination.  A  planetary  nebula  is  included  in  1564. 
With  very  powerful  telescopes  this  nebula  has  been  seen 
ring-shaped.  2  1146,  otherwise  known  as  5  Navis,  is  a 
pretty  double,  colors  pale  yellow  and  blue,  magnitudes 
five  and  seven,  distance  3.25",  p.  19°.  Our  three-inch  will 
suffice  for  this. 

North  of  Canis  Major  and  Argo  we  find  Monoceros  and 
Canis  Minor  (map  No.  3).  The  stars  forming  the  western 
end  of  Monoceros  are  depicted  on  map  No.  1.  We  shall 
begin  with  these.  The  most  interesting  and  beautiful  is 
11,  a  fine  triple  star,  magnitudes  five,  six,  and  seven, 
distances  7.4",  p.  131°,  and  2.7",  p.  103°.  Sir  William  Her- 
schel  regarded  this  as  one  of  the  most  beautiful  sights  in 
the  heavens.  It  is  a  good  object  to  try  our  three-inch  on, 
although  it  should  not  be  difficult  for  such  an  aperture. 
The  star  4  is  also  a  triple,  magnitudes  six,  ten,  and  eleven, 
distances  3.4",  p.  178°,  and  10",  p.  244°.  We  should  glance 
at  the  star  5  to  admire  its  fine  orange  color.  In  8  we  find 
a  golden  fifth-magnitude  star,  combined  with  a  blue  or 
lilac  star  of  the  seventh  magnitude,  distance  14",  p.  24°. 
2  938  is  a  difficult  double,  magnitudes  six  and  a  half  and 
twelve,  distance  10",  p.  210°.  2  921  is  double,  magnitudes 
six  and  a  half  and  eight,  distance  16",  p.  4°.  At  the  spot 
marked  on  the  map  1424  we  find  an  interesting  cluster 
containing  one  star  of  the  sixth  magnitude. 

The  remaining  stars  of  Monoceros  will  be  found  on 
map  No.  3.  The  double  and  triple  stars  to  be  noted  are  S, 
or  2  950  (which  is  also  a  variable  and  involved  in  a  faint 
nebula),  magnitudes  six  and  nine,  distance  2.5",  p.  206°; 
21183,  double,  magnitudes  five  and  a  half  and  eight,  dis- 
tance 31",  p.  326°;  2  1190,  triple,  magnitudes  five  and  a 
half,  ten,  and  nine,  distances  31",  p.  105°,  and  67",  p.  244°. 


36  PLEASURES  OF  THE  TELESCOPE 

The  clusters  are  1465,  which  has  a  minute  triple  star  near 
the  center;  1483,  one  member  of  whose  swarm  is  red; 
1611,  very  small  but  rich;  and  1637,  interesting  for  the 
great  number  of  ninth-magnitude  £tars  that  it  contains. 
We  should  use  the  five-inch  for  all  of  these. 

Canis  Minor  and  the  Head  of  Hydra  are  also  contained 
on  map  No.  3.  Procyon,  a  of  Canis  Minor,  has  several  mi- 
nute stars  in  the  same  field  of  view.  There  is,  besides,  a 
companion  which,  although  it  was  known  to  exist,  no  tele- 
scope was  able  to  detect  until  November,  1896.  It  must  be 

of  immense  mass,  since 
its  attraction  causes 
perceptible  perturba- 
tions in  the  motion  of 
Procyon.  Its  magni- 
tude is  eight  and  a 
half,  distance  4.83",  p. 
338°.  One  of  the  small 
stars  just  referred  to, 
the  second  one  east  of 
Procyon,  distant  one 
third  of  the  moon's  di- 
ameter, is  an  interest- 

PROCYON  AND  ITS  NEIGHBORS. 

ing  double.  Our  four- 
inch  may  separate  it,  and  the  five-inch  is  certain  to  do  so. 
The  magnitudes  are  seven  and  seven  and  a  half  or  eight, 
distance  1.2",  p.  133°.  This  star  is  variously  named  2  1126 
and  31  Can.  Min.  Bode.  Star  No.  14  is  a  wide  triple,  mag- 
nitudes six,  seven,  and  eight,  distances  75,  p.  65°,  and  115", 
p.  154°. 

In  the  Head  of  Hydra  we  find  2  1245,  a  double  of  the 
sixth  and  seventh  magnitudes,  distance  10.5",  p.  25°.  The 
larger  star  shows  a  fine  yellow.  In  e  we  have  a  beautiful 
combination  of  a  yellow  with  a  blue  star,  magnitudes  four 


IN  THE  STARRY  HEAVENS  37 

and  eight,  distance  3.4",  p.  198°.  Finally,  let  us  look  at  0 
for  a  light  test  with  the  five-inch.  The  two  stars  com- 
posing it  are  of  the  fourth  and  twelfth  magnitudes,  dis- 
tance 50",  p.  170°. 

The  brilliant  constellations  of  Gemini  and  Taurus 
tempt  us  next,  but  warning  clouds  are  gathering,  and  we 
shall  do  well  to  house  our  telescopes  and  warm  our  fingers 
by  the  winter  fire.  There  will  be  other  bright  nights,  and 
the  stars  are  lasting. 


CHAPTER  III 

FROM  GEMINI  TO  LEO  AND  ROUND  ABOUT 

"If  thou  wouldst  gaze  on  starry  Charioteer, 
And  hast  heard  legends  of  the  wondrous  Goat, 
Vast  looming  shalt  thou  find  on  the  Twins'  left, 
His  form  bowed  forward." — POSTE'S  ARATUS. 

THE  zodiacal  constellations  of  Gemini,  Cancer,  and 
Leo,  together  with  their  neighbors  Auriga,  the  Lynx, 
Hydra,  Sextans,  and  Coma  Berenices,  will  furnish  an 
abundance  of  occupation  for  our  second  night  at  the  tele- 
scope. We  shall  begin,  using  our  three-inch  glass,  with  a, 
the  chief  star  of  Gemini  (map  No.  4).  This  is  ordinarily 
known  as  Castor.  Even  an  inexperienced  eye  perceives 
at  once  that  it  is  not  as  bright  as  its  neighbor  Pollux,  P. 
Whether  this  fact  is  to  be  regarded  as  indicating  that 
Castor  was  brighter  than  Pollux  in  1603,  when  Bayer  at- 
tached their  Greek  letters,  is  still  an  unsettled  question. 
Castor  may  or  may  not  be  a  variable,,  but  it  is,  at  any  rate, 
one  of  the  most  beautiful  double  stars  in  the  heavens.  A 
power  of  one  hundred  is  amply  sufficient  to  separate  its 
components,  whose  magnitudes  are  about  two  and  three, 
the  distance  between  them  being  6",  p.  226°.  A  slight 
yet  distinct  tinge  of  green,  recalling  that  of  the  Orion 
nebula,  gives  a  peculiar  appearance  to  this  couple.  Green 
is  one  of  the  rarest  colors  among  the  stars.  Castor  be- 
longs to  the  same  general  spectroscopic  type  in  which 
Sirius  is  found,  but  its  lines  of  hydrogen  are  broader  than 
those  seen  in  the  spectrum  of  the  Dog  Star.  There  is 

38 


40  PLEASURES   OF  THE  TELESCOPE 

reason  for  thinking  that  it  may  be  surrounded  with  a 
more  extensive  atmosphere  of  that  gaseous  metal  called 
hydrogen  than  any  other  bright  star  possesses.  There 
seems  to  be  no  doubt  that  the  components  of  Castor  are 
in  revolution  around  their  common  center  of  gravity, 
although  the  period  is  uncertain,  varying  in  different  esti- 
mates all  the  way  from  two  hundred  and  fifty  to  one  thou- 
sand years;  the  longer  estimate  is  probably  not  far  from 
the  truth.  There  is  a  tenth-magnitude  star,  distance  73", 
p.  164°,  which  may  belong  to  the  same  system. 

From  Castor  let  us  turn  to  Pollux,  at  the  same  time 
exchanging  our  three-inch  telescope  for  the  four-inch,  or, 
still  better,  the  five-inch.  Pollux  has  five  faint  compan- 
ions, of  which  we  may  expect  to  see  three,  as  follows: 
Tenth  magnitude,  distance  175",  p.  70°;  nine  and  a  half 
magnitude,  distance  206",  p.  90°,  and  ninth  magnitude, 
distance  229",  p.  75°.  Burnham  has  seen  a  star  of  thir- 
teen and  a  half  magnitude,  distance  43",  p.  275°,  and  has 
divided  the  tenth-magnitude  star  into  two  components, 
only  1.4"  apart,  the  smaller  being  of  the  thirteenth  mag- 
nitude, and  situated  at  the  angle  128°.  A  calculation 
based  on  Dr.  Elkin's  parallax  of  0.068"  for  Pollux  shows 
that  that  star  may  be  a  hundredfold  more  luminous  than 
the  sun,  while  its  nearest  companion  may  be  a  body 
smaller  than  our  planet  Jupiter,  but  shining,  of  course,  by 
its  own  light.  Its  distance  from  Pollux,  however,  exceeds 
that  of  Jupiter  from  the  sun  in  the  ratio  of  about  one  hun- 
dred and  thirty  to  one. 

In  the  double  star  IT  we  shall  find  a  good  light  test  for 
our  three-inch  aperture,  the  magnitudes  being  six  and 
eleven,  distance  22",  p.  212°.  The  four-inch  will  show 
that  K  is  a  double,  magnitudes  four  and  ten,  distance  6", 
p.  232°.  The  smaller  star  is  of  a  delicate  blue  color,  and 
it  has  been  suspected  of  variability.  That  it  may  be  vari- 


FROM  GEMINI  TO  LEO  AND  HOUND  ABOUT  41 

able  is  rendered  the  more  probable  by  the  fact  that  in  the 
immediate  neighborhood  of  K  there  are  three  undoubted 
variables,  S,  T,  and  U,  and  there  appears  to  be  some  mys- 
terious law  of  association  which  causes  such  stars  to 
group  themselves  in  certain  regions.  None  of  the  vari- 
ables just  named  ever  become  visible  to  the  naked  eye, 
although  they  all  undergo  great  changes  of  brightness, 
sinking  from  the  eighth  or  ninth  magnitude  down  to  the 
thirteenth  or  even  lower.  The  variable  R,  which  lies  con- 
siderably farther  west,  is  well  worth  attention  because  of 
the  remarkable  change  of  color  which  it  sometimes  ex- 
hibits. It  has  been  seen  blue,  red,  and  yellow  in  succes- 
sion. It  varies  from  between  the  sixth  and  seventh  mag- 
nitudes to  less  than  the  thirteenth  in  a  period  of  about 
two  hundred  and  forty-two  days. 

Not  far  away  we  find  a  still  more  curious  variable  f; 
this  is  also  an  interesting  triple  star,  its  principal  compo- 
nent being  a  little  under  the  third  magnitude,  while  one 
of  the  companions  is  of  the  seventh  magnitude,  distance 
90",  p.  355°,  and  the  other  is  of  the  eleventh  magnitude  or 
less,  distance  65",  p.  85°.  We  should  hardly  expect  to  see 
the  fainter  companion  with  the  three-inch.  The  principal 
star  varies  from  magnitude  three  and  seven  tenths  down 
to  magnitude  four  and  a  half  in  a  period 
of  a  little  more  than  ten  days. 

With  the  four-  or  five-inch  we  get  a 
very  pretty  sight  in  8,  which  appears  split 
into  a  yellow  and  a  purple  star,  magni- 
tudes three  and  eight,  distance  7",  p.  206°. 

Near     S,    toward    the    east,  lies    One    Of        WONDERFUL  NEBULA  IN 

GEMINI  (1532). 

the   strangest   of   all   the   nebula.      (See 
the  figures  1532  on  the  map.)     Our  telescopes  will  show 
it  to  us  only  as  a  minute  star  surrounded  with  a  nebu- 
lous  atmosphere,   but   its   appearance   with   instruments- 


42  PLEASURES  OF  THE  TELESCOPE 

of  the  first  magnitude  is  so  astonishing  and  at  the  same 
time  so  beautiful  that  I  can  not  refrain  from  giving 
a  brief  description  of  it  as  I  saw.  it  in  1893  with  the 
great  Lick  telescope.  In  the  center  glittered  the  star, 
and  spread  evenly  around  it  was  a  circular  nebulous  disk, 
pale  yet  sparkling  and  conspicuous.  This  disk  was  sharp- 
ly bordered  by  a  narrow  black  ring,  and  outside  the  ring 
the  luminous  haze  of  the  nebula  again  appeared,  gradu- 
ally fading  toward  the  edge  to  invisibility.  The  accom- 
panying cut,  which  exaggerates  the  brightness  of  the 
nebula  as  compared  with  the  star,  gives  but  a  faint  idea 
of  this  most  singular  object.  If  its  peculiarities  were 
within  the  reach  of  ordinary  telescopes,  there  are  few 
scenes  in  the  heavens  that  would  be  deemed  equally  ad- 
mirable. 

In  the  star  rj  we  have  another  long-period  variable, 
which  is  also  a  double  star;  unfortunately  the  companion, 
being  of  only  the  tenth  magnitude  and  distant  less  than  1" 
from  its  third-magnitude  primary,  is  beyond  the  reach  of 
our  telescopes.  But  y  points  the  way  to  one  of  the  finest 
star  clusters  in  the  sky,  marked  1360  on  the  map.  The 
naked  eye  perceives  that  there  is  something  remarkable 
in  that  place,  and  the  opera  glass  faintly  reveals  its  dis- 
tant splendors,  but  the  telescope  fairly  carries  us  into  its 
presence.  Its  stars  are  innumerable,  varying  from  the 
ninth  magnitude  downward  to  the  last  limit  of  visibility, 
and  presenting  a  wonderful  array  of  curves  which  are 
highly  interesting  from  the  point  of  view  of  the  nebular 
origin  of  such  clusters.  Looking  backward  in  time,  with 
that  theory  to  guide  us,  we  can  see  spiral  lines  of  nebulous 
mist  occupying  the  space  that  now  glitters  with  inter- 
lacing rows  of  stars.  It  is  certainly  difficult  to  under- 
stand how  such  lines  of  nebula  could  become  knotted  with 
the  nuclei  of  future  stars,  and  then  gradually  be  absorbed 


FROM  GEMINI  TO  LEO  AND  ROUND  ABOUT  43 

into  those  stars;  and  yet,  if  such  a  process  does  not  occur, 
what  is  the  meaning  of  that  narrow  nebulous  streak  in 
the  Pleiades  along  which  five  or  six  stars  are  strung  like 
beads  on  a  string?  The  surroundings  of  this  cluster, 
1360,  as  one  sweeps  over  them  with  the  telescope  gradu- 
ally drawing  toward  the  nucleus,  have  often  reminded  me 
of  the  approaches  to  such  a  city  as  London.  Thicker  and 
closer  the  twinkling  points  become,  until  at  last,  as  the 
observer's  eye  follows  the  gorgeous  lines  of  stars  trend- 
ing inward,  he  seems  to  be  entering  the  streets  of  a  bril- 
.liantly  lighted  metropolis. 

Other  objects  in  Gemini  that  we  can  ill  miss  are:  A6, 
double,  magnitudes  three  and  eleven,  distance  73",  p.  76°, 
colors  yellow  and  blue;  15,  double,  magnitudes  six  and 
eight,  distance  33",  p.  205°;  7,  remarkable  for  array  of 
small  stars  near  it;  38,  double,  magnitudes  six  and  eight, 
distance  6.5",  p.  162°,  colors  yellow  and  blue  (very  pretty); 
X,  double,  magnitudes  four  and  eleven,  distance  10",  p.  30°, 
color  of  larger  star  blue — try  with  the  five-inch;  e,  double, 
magnitudes  three  and  nine,  distance  110",  p.  94°. 

From  Gemini  we  pass  to  Cancer.  This  constellation 
has  no  large  stars,  but  its  great  cluster  Praesepe  (1681  on 
map  No.  4)  is  easily  seen  as  a  starry  cloud  with  the  naked 
eye.  With  the  telescope  it  presents  the  most  brilliant  ap- 
pearance with  a  very  low  power.  It  was  one  of  the  first 
objects  that  Galileo  turned  to  when  he  had  completed  his 
telescope,  and  he  wonderingly  counted  its  stars,  of  which 
he  enumerated  thirty-six,  and  made  a  diagram  showing 
their  positions. 

The  most  interesting  star  in  Cancer  is  £,  a  celebrated 
triple.  The  magnitudes  of  its  components  are  six,  seven, 
and  seven  and  a  half;  distances  1.14",  p.  6°,  and  5.7",  p. 
114°.  We  must  use  our  five-inch  glass  in  order  satisfac- 
torily to  separate  the  two  nearest  stars.  The  gravita- 


44  PLEASURES  OF  THE   TELESCOPE 

tional  relationship  of  the  three  stars  is  very  peculiar. 
The  nearest  pair  revolve  around  their  common  center  in 
about  fifty-eight  years,  while  the  third  star  revolves  with 
the  other  two,  around  a  center  common  to  all  three,  in  a 
period  of  six  or  seven  hundred  years.  But  the  movements 
of  the  third  star  are  erratic,  and  inexplicable  except  upon 
the  hypothesis  advanced  by  Seeliger,  that  there  is  an  in- 
visible, or  dark,  star  near  it  by  whose  attraction  its  mo- 
tion is  perturbed. 

In  endeavoring  to  picture  the  condition  of  things  in  f 
Cancri  we  might  imagine  our  sun  to  have  a  companion  sun,  • 
a  half  or  a  third  as  large  as  itself,  and  situated  within  what 
may  be  called  planetary  distance,  circling  with  it  around 
their  center  of  gravity;  while  a  third  sun,  smaller  than 
the  second  and  several  times  as  far  away,  and  accom- 
panied by  a  black  or  non-luminous  orb,  swings  with  the 
first  two  around  another  center  of  motion.  There  you 
would  have  an  entertaining  complication  for  the  inhabit- 
ants of  a  system  of  planets! 

Other  objects  in  Cancer  are:  2  1223,  double  star,  mag- 
nitudes six  and  six  and  a  half,  distance  5",  p.  214°;  2  1291, 
double,  magnitudes  both  six,  distance  1.3",  p.  328° — four- 
inch  should  split  it;  *,  double,  magnitudes  four  and  a  half 
and  six  and  a  half,  distance  30",  p.  308° ;  66,  double  magni- 
tudes six  and  nine,  distance  4.8",  p.  136°;  21311,  double, 
magnitudes  both  about  the  seventh,  distance  7",  p.  200° ; 
1712,  star  cluster,  very  beautiful  with  the  five-inch  glass. 

The  constellation  of  Auriga  may  next  command  our 
attention  (map  No.  5).  The  calm  beauty  of  its  leading 
star  Capella  awakens  an  admiration  that  is  not  dimin- 
ished by  the  rivalry  of  Orion's  brilliants  glittering  to  the 
south  of  it.  Although  Capella  must  be  an  enormously 
greater  sun  than  ours,  its  spectrum  bears  so  much  resem- 
blance  to  the  solar  spectrum  that  a  further  likeness  of 


46  PLEASURES  OF  THE  TELESCOPE 

condition  is  suggested.  No  close  telescopic  companion  to 
Capella  has  been  discovered.  A  ninth-magnitude  com- 
panion, distant  159",  p.  146°,  and  two  others,  one  of 
twelfth  magnitude  at  78",  p.  317°,  and  the  other  of  thir- 
teenth magnitude  at  126",  p.  183°,  may  be  distant  satel- 
lites of  the  great  star,  but  not  planets  in  the  ordinary 
sense,  since  it  is  evident  that  they  are  self-luminous. 
It  is  a  significant  fact  that  most  of  the  first-magnitude 
stars  have  faint  companions  which  are  not  so  distant 
as  altogether  to  preclude  the  idea  of-  physical  relation- 
ship. 

But  while  Capella  has  no  visible  companion,  Campbell, 
of  the  Lick  Observatory,  has  lately  discovered  that  it  is  a 
conspicuous  example  of  a  peculiar  class  of  binary  stars 
only  detected  within  the  closing  decade  of  the  nineteenth 
century.  The  nature  of  these  stars,  called  spectroscopic 
binaries,  may  perhaps  best  be  described  while  we  turn 
our  attention  from  Capella  to  the  second  star  in  Auriga  0 
(Menkalina),  which  not  only  belongs  to  the  same  class, 
but  was  the  first  to  be  discovered.  Neither  our  tele- 
scopes, nor  any  telescope  in  existence,  can  directly  reveal 
the  duplicity  of  fi  Auriga  to  the  eye — i.  e.,  we  can  not 
see  the  two  stars  composing  it,  because  they  are  so 
close  that  their  light  remains  inextricably  mingled  after 
the  highest  practicable  magnifying  power  has  been  ap- 
plied in  the  effort  to  separate  them.  But  the  spectro- 
scope shows  that  the  star  is  double  and  that  its  compo- 
nents are  in  rapid  revolution  around  one  another,  com- 
pleting their  orbital  swing  in  the  astonishingly  short 
period  of  four  days!  The  combined  mass  of  the  two  stars 
is  estimated  to  be  two  and  a  half  times  the  mass  of  the 
sun,  and  the  distance  between  them,  from  center  to  center, 
is  about  eight  million  miles. 

The  manner  in  which  the  spectroscope  revealed  the 


FROM  GEMINI  TO  LEO  AND  ROUND  ABOUT  47 

existence  of  two  stars  in  /9  Auriga?  is  a  beautiful  illustra- 
tion of  the  unexpected  and,  so  to  speak,  automatic  appli- 
cation of  an  old  principle  in  the  discovery  of  new  facts 
not  looked  for.  It  was  noticed  at  the  Harvard  Observa- 
tory that  the  lines  in  the  photographed  spectrum  of  /Q 
Auriga?  (and  of  a  few  other  stars  to  be  mentioned  later) 
appeared  single  in  some  of  the  photographs  and  double 
in  others.  Investigation  proved  that  the  lines  were 
doubled  at  regular  intervals  of  about  two  days,  and  that 
they  appeared  single  in  the  interim.  The  explanation 
was  not  far  to  seek.  It  is  known  that  all  stars  which  are 
approaching  us  have  their  spectral  lines  shifted,  by  virtue 
of  their  motion  of  approach,  toward  the  violet  end  of  the 
spectrum,  and  that,  for  a  similar  reason,  all  stars  which 
are  receding  have  their  lines  shifted  toward  the  red  end 
of  the  spectrum.  Now,  suppose  two  stars  to  be  revolving 
around  one  another  in  a  plane  horizontal,  or  nearly  so,  to 
the  line  of  sight.  When  they  are  at  their  greatest  angu- 
lar distance  apart  as  seen  from  the  earth  one  of  them 
will  evidently  be  approaching  at  the  same  moment  that 
the  other  is  receding.  The  spectral  lines  of  the  first  will 
therefore  be  shifted  toward  the  violet,  and  those  of  the 
second  will  be  shifted  toward  the  red.  Then  if  the  stars, 
when  at  their  greatest  distance  apart,  are  still  so  close 
that  the  telescope  can  not  separate  them,  their  light  will 
be  combined  in  the  spectrum;  but  the  spectral  lines,  being 
simultaneously  shifted  in  opposite  directions,  will  neces- 
sarily appear  to  be  doubled.  As  the  revolution  of  the 
stars  continues,  however,  it  is  clear  that  their  motion  will 
soon  cease  to  be  performed  in  the  line  of  sight,  and  will 
become  more  and  more  athwart  that  line,  and  as  this  oc- 
curs the  spectral  lines  will  gradually  assume  their  normal 
position  and  appear  single.  This  is  the  sequence  of  phe- 
nomena in  /3  Auriga?.  And  the  same  sequence  is  found  in 


48  PLEASURES  OF  THE  TELESCOPE 

Capella  and  in  several  other  more  or  less  conspicuous 
stars  in  various  parts  of  the  heavens. 

Such  facts,  like  those  connecting  rows  and  groups  of 
stars  with  masses  and  spiral  lines  of -nebula  are  obscure 
signboards,  indicating  the  opening  of  a  way  which,  start- 
ing in  an  unexpected  direction,  leads  deep  into  the  mys- 
teries of  the  universe. 

Southward  from  $  we  find  the  star  0,  which  is  a  beauti- 
ful quadruple.  We  shall  do  best  with  our  five-inch  here, 
although  in  a  fine  condition  of  the  atmosphere  the  four- 
inch  might  suffice.  The  primary  is  of  the  third  magni- 
tude; the  first  companion  is  of  magnitude  seven  and  a 
half,  distance  2",  p.  5°;  the  second,  of  the  tenth  magni- 
tude, distance  45",  p.  292°;  and  the  third,  of  the  tenth 
magnitude,  distance  125",  p.  350°. 

We  should  look  at  the  double  2  616  with  one  of  our 
larger  apertures  in  order  to  determine  for  ourselves  what 
the  colors  of  the  components  are.  There  is  considerable 
diversity  of  opinion  on  this  point.  Some  say  the  larger 
star  is  pale  red  and  the  smaller  light  blue;  others  con- 
sider the  color  of  the  larger  star  to  be  greenish,  and  some 
have  even  called  it  white.  The  magnitudes  are  five  and 
nine,  distance  6",  p.  350°.  . 

Auriga  contains  several  noteworthy  clusters  which 
will  be  found  on  the  map.  The  most  beautiful  of  these  is 
1295,  in  which  about  five  hundred  stars  have  been  counted. 

The  position  of  the  new  star  of  1892,  known  as  Nova 
Aurigse,  is  also  indicated  on  the  map.  While  this  never 
made  a  brilliant  appearance,  it  gave  rise  to  a  greater  va- 
riety of  speculative  theories  than  any  previous  phenome- 
non of  the  kind.  Although  not  recognized  until  January 
24,  1892,  this  star,  as  photographic  records  prove,  was  in 
existence  on  December  9,  1891.  At  its  brightest  it  barely 
exceeded  magnitude  four  and  a  half,  and  its  maximum 


FROM  GEMINI  TO  LEO  AND  ROUND  ABOUT  49 

occurred  within  ten  days  after  its  first  recognition. 
When  discovered  it  was  of  the  fifth  magnitude.  It  was 
last  seen  in  its  original  form  with  the  Lick  telescope  on 
April  26th,  when  it  had  sunk  to  the  lowest  limit  of  visibil- 
ity. To  everybody's  astonishment  it  reappeared  in  the 
following  August,  and  on  the  17th  of  that  month  was  seen 
shining  with  the  light  of  a  tenth-magnitude  star,  but  pre- 
senting the  spectrum  of  a  nebula!  Its  visual  appearance  in 
the  great  telescope  was  now  also  that  of  a  planetary 
nebula.  Its  spectrum  during  the  first  period  of  its  visi- 
bility had  been  carefully  studied,  so  that  the  means  ex- 
isted for  making  a  spectroscopic  comparison  of  the  phe- 
nomenon in  its  two  phases.  During  the  first  period,  when 
only  a  stellar  spectrum  was  noticed,  remarkable  shiftings 
of  the  spectral  lines  occurred,  indicating  that  two  and 
perhaps  three  bodies  were  concerned  in  the  production  of 
the  light  of  the  new  star,  one  of  which  was  approaching 
the  earth,  while  the  other  or  the  others  receded  with  ve- 
locities of  several  hundred  miles  per  second!  On  the 
revival  in  the  form  of  a  planetary  nebula,  while  the  char- 
acter of  the  spectrum  had  entirely  changed,  evidences  of 
rapid  motion  in  the  line  of  sight  remained. 

But  what  was  the  meaning  of  all  this?  Evidently  a 
catastrophe  of  some  kind  had  occurred  out  there  in  space. 
The  idea  of  a  collision  involving  the  transformation  of 
the  energy  of  motion  into  that  of  light  and  heat  suggests 
itself  at  once.  But  what  were  the  circumstances  of 
the  collision?  Did  an  extinguished  sun,  flying  blindly 
through  space,  plunge  into  a  vast  cloud  of  meteoric  parti- 
cles, and,  under  the  lashing  impact  of  so  many  myriads  of 
missiles,  break  into  superficial  incandescence,  while  the 
cosmical  wrack  through  which  it  had  driven  remained 
glowing  with  nebulous  luminosity?  Such  an  explanation 
has  been  offered  by  Seeliger.  Or  was  Vogel  right  when 


50  PLEASURES  OF  THE  TELESCOPE 

he  suggested  that  Nova  Auriga?  could  be  accounted  for  by 
supposing  that  a  wandering  dark  body  had  run  into  colli- 
sion with  a  system  of  planets  surrounding  a  decrepit  sun 
(and  therefore  it  is  to  be  "hoped  uninhabited),  and  that 
those  planets  had  been  reduced  to  vapor  and  sent  spin- 
ning by  the  encounter,  the  second  outburst  of  light  being 
caused  by  an  outlying  planet  of  the  system  falling  a  prey 
to  the  vagabond  destroyer?  Or  some  may  prefer  the  ex- 
planation, based  on  a  theory  of  Wilsing's,  that  two  great 
bodies,  partially  or  wholly  opaque  and  nonluminous  at 
their  surfaces,  but  liquid  hot  within,  approached  one  an- 
other so  closely  that  the  tremendous  strain  of  their  tidal 
attraction  burst  their  shells  asunder  so  that  their  bowels 
of  fire  gushed  briefly  visible,  amid  a  blaze  of  spouting 
vapors.  And  yet  Lockyer  thinks  that  there  was  no  solid 
or  semisolid  mass  concerned  in  the  phenomenon  at  all,  but 
that  what  occurred  was  simply  the  clash  of  two  immense 
swarms  of  meteors  that  had  crossed  one  another's  track. 

Well,  where  nobody  positively  knows,  everybody  has 
free  choice.  In  the  meantime,  look  at  the  spot  in  the 
sky  where  that  little  star  made  its  appearance  and  under- 
went its  marvelous  transformation,  for,  even  if  you  can 
see  no  remains  of  it  there,  you  will  feel  your  interest  in 
the  problem  it  has  presented,  and  in  the  whole  subject  of 
astronomy,  greatly  heightened  and  vivified,  as  the  visitor 
to  the  field  of  Waterloo  becomes  a  lover  of  history  on 
the  spot. 

The  remaining  objects  of  special  interest  in  Auriga 
may  be  briefly  mentioned:  26,  triple  star,  magnitudes  five, 
eight,  and  eleven,  distances  12",  p.  268°,  and  26",  p.  113°; 
14,  triple  star,  magnitudes  five,  seven  and  a  half,  and 
eleven,  distances  14",  p.  224°,  and  12.6",  p.  342°,  the  last 
difficult  for  moderate  apertures;  X,  double,  magnitudes 
five  and  nine,  distance  121",  p.  13°;  e,  variable,  generally 


FROM  GEMINI  TO  LEO  AND  HOUND  ABOUT  51 

• 

of  third  magnitude,  but  has  been  seen  of  only  four  and 
a  half  magnitude;  41,  double,  magnitudes  five  and  six, 
distance  8",  p.  354°;  996,  1067,  1119,  and  1166,  clusters  all 
well  worth  inspection,  1119  being  especially  beautiful. 

The  inconspicuous  Lynx  furnishes  some  fine  telescopic 
objects,  all  grouped  near  the  northwestern  corner  of  the 
constellation.  Without  a  six-inch  telescope  it  would  be  a 
waste  of  time  to  attack  the  double  star  4,  whose  compo- 
nents are  of  sixth  and  eighth  magnitudes,  distance  0.8", 
p.  103°;  but  its  neighbor,  5,  a  fine  triple,  is  within  our 
reach,  the  magnitudes  being  six,  ten,  and  eight,  distances 
30",  p.  139°,  and  96",  p.  272°.  In  12  Lyncis  we  find  one  of 
the  most  attractive  of  triple  stars,  which  in  good  seeing 
weather  is  not  beyond  the  powers  of  a  three-inch  glass, 
although  we  shall  have  a  far  more  satisfactory  view  of  it 
with  the  four-inch.  The  components  are  of  the  sixth, 
seventh,  and  eighth  magnitudes,  distances  1.4",  p.  117°, 
and  8.7",  p.  304°.  A  magnifying  power  which  just  suffices 
clearly  to  separate  the  disks  of  the  two  nearer  stars 
makes  this  a  fine  sight.  A  beautiful  contrast  of  colors 
belongs  to  the  double  star  14,  but  unfortunately  the  star 
is  at  present  very  close,  the  distance  between  its  sixth  and 
seventh  magnitude  components  not  exceeding  0.8",  posi- 
tion angle  64°.  2  958  is  a  pretty  double,  both  stars  being 
of  the  sixth  magnitude,  distance  5",  p.  257°.  Still  finer 
is  2  1009,  a  double,  whose  stars  are  both  a  little  above  the 
seventh  magnitude  and  nearly  equal,  distance  3",  p.  156°. 
A  low  power  suffices  to  show  the  three  stars  in  19,  their 
magnitudes  being  six  and  a  half,  seven  and  a  half,  and 
eight,  distances  15",  p.  312°,  and  215",  p.  358°.  Webb  de- 
scribes the  two  smaller  stars  as  plum-colored.  Plum-col- 
ored suns! 

At  the  opposite  end  of  the  constellation  are  two  fine 
doubles,  2  1333,  magnitudes  six  and  a  half  and  seven,  dis- 


52  PLEASURES  OF  THE  TELESCOPE 

tance  1.4",  p.  39°;  and  38,  magnitudes  four  and  seven,  dis- 
tance 2.9",  p.  235°. 

Under  the  guidance  of  map  No.  6  we  turn  to  Leo,  which 
contains  one  of  the  leading  gems  anjbng  the  double  stars, 
7,  whose  components,  of  the  second  and  fourth  magnitudes, 
are  respectively  yellow  and  green,  the  green  star,  accord- 
ing to  some  observers,  having  a  peculiar  tinge  of  red. 
Their  distance  apart  is  3.7",  p.  118°,  and  they  are  un- 
doubtedly in  revolution  about  a  common  center,  the  prob- 
able period  being  about  four  hundred  years.  The  three- 
inch  glass  should  separate  them  easily  when  the  air  is 
steady,  and  a  pleasing  sight  they  are. 

The  star  i  is  a  closer  double,  and  also  very  pretty,  mag- 
nitudes four  and  eight,  colors  lemon  and  light  blue,  dis- 
tance 2.17",  p.  53°.  Other  doubles  are  T,  magnitudes  five 
and  seven,  distance  95",  p.  170°;  88,  magnitudes  seven  and 
nine,  distance  15",  p.  320°;  90,  triple,  magnitudes  six, 
seven  and  a  half,  and  ten,  distance,  3.5",  p.  209°,  and  59", 
p.  234°;  54,  magnitudes  four  and  a  half  and  seven,  dis- 
tance 6.2",  p.  102°;  and  49,  magnitudes  six  and  nine,  dis- 
tance 2.4",  p.  158°. 

Leo  contains  a  remarkable  variable  star,  K,  deep  red 
in  color,  and  varying  in  a  space  of  a  hundred  and  forty- 
four  days  from  the  fifth  to  the  tenth  magnitude.  It  has 
also  several  nebulae,  of  which  only  one  needs  special  men- 
tion, No.  1861.  This  is  spindle-shaped,  and  large  tele- 
scopes show  that  it  consists  of  three  nebula?.  The  ob- 
server with  ordinary  instruments  finds  little  to  see  and 
little  to  interest  him  in  these  small,  faint  nebulae. 

We  may  just  glance  at  two  double  stars  in  the  small 
constellation  of  Sextans,  situated  under  Leo.  These  are: 
9,  magnitudes  seven  and  eight,  distance  53",  p.  292°;  and 
35,  magnitudes  six  and  seven,  distance  6.9",  p.  240°. 

Coma  Berenices  (map  No.  6)  includes  several  interest- 


54  PLEASURES   OF  THE   TELESCOPE 

ing  objects.  Let  us  begin  with  the  star  2,  a  double,  of 
magnitudes  six  and  seven  and  a  half,  distance  3.6",  p.  240°. 
The  color  of  the  smaller  s^tar  is  lilac.  This  hue,  although 
not  extremely  uncommon  among ;  double  stars  elsewhere, 
recurs  again  and  again,  with  singular  persistence,  in  this 
little  constellation.  For  instance,  in  the  very  next  star 
that  we  look  at,  12,  we  find  a  double  whose  smaller  com- 
ponent is  lilac.  The  magnitudes  in  12  are  five  and  eight, 
distance  66",  p.  168°.  So  also  the  wide  double  17,  magni- 
tudes five  and  a  half  and  six,  distance  145",  exhibits  a 
tinge  of  lilac  in  the  smaller  component;  the  triple  35,  mag- 
nitudes five,  eight,  and  nine,  distances  1",  p.  77°,  and 
28.7",  p.  124°,  has  for  colors  yellow,  lilac,  and  blue,  and  the 
double  24,  magnitudes  five  and  six,  distance  20",  p.  270°, 
combines  an  orange  with  a  lilac  star,  a  very  striking  and 
beautiful  contrast.  We  should  make  a  mistake  if  we 
regarded  this  wonderful  distribution  of  color  among  the 
double  stars  as  accidental.  It  is  manifestly  expressive  of 
their  physical  condition,  although  we  can  not  yet  decipher 
its  exact  meaning. 

The  binary  42  Coma?  Berenicis  is  too  close  for  ordinary 
telescopes,  but  it  is  highly  interesting  as  an  intermediate 
between  those  pairs  which  the  telescope  is  able  to  sepa- 
rate and  those — like  ft  Aurigse — which  no  magnifying 
power  can  divide,  but  which  reveal  the  fact  that  they  are 
double  by  the  periodical  splitting  of  their  spectral  lines. 
The  orbit  in  42  Comae  Berenicis  is  a  very  small  one,  so  that 
even  when  the  components  are  at  their  greatest  distance 
apart  they  can  not  be  separated  by  a  five-  or  six-inch  glass. 
Burnham,  using  the  Lick  telescope,  in  1890  made  the  dis- 
tance 0.7";  Hall,  using  the  Washington  telescope,  in  1891 
made  it  a  trifle  more  than  0.5".  He  had  measured  it  in 
1886  as  only  0.27".  The  period  of  revolution  is  believed 
to  be  about  twenty-five  years. 


56  PLEASURES  OF  THE  TELESCOPE 

In  Coma  Berenices  there  is  an  outlying  field  of  the  mar- 
velous nebulous  region  of  Virgo,  which  we  may  explore 
on  some  future  evening.  .But  the .  nebulae  in  Coma  are 
very  faint,  and,  for  an  amateur,  hardly  worth  the  trouble 
required  to  pick  them  up.  The  two  clusters  included  in 
the  map,  2752  and  3453,  are  bright  enough  to  repay  inspec- 
tion with  our  largest  aperture. 

Although  Hydra  is  the  largest  constellation  in  the 
heavens,  extending  about  seven  hours,  or  105°,  in  right 
ascension,  it  contains  comparatively  few  objects  of  inter 
est,  and  most  of  these  are  in  the  head  or  western  end  of 
the  constellation,  which  we  examined  during  our  first 
night  at  the  telescope.  In  the  central  portion  of  Hydra, 
represented  on  map  No.  7,  we  find  its  leading  star  a,  some- 
times called  Alphard,  or  Cor  Hydra?,  a  bright  second-mag- 
nitude star  that  has  been  suspected  of  variability.  It  has 
a  decided  orange  tint,  and  is  accompanied,  at  a  distance 
of  281",  p.  153°,  by  a  greenish  tenth-magnitude  star.  Bu. 
339  is  a  fine  double,  magnitudes  eight  and  nine  and  a  half, 
distance  1.3",  p.  216°.  The  planetary  nebula  2102  is  about 
V  in  diameter,  pale  blue  in  color,  and  worth  looking  at, 
because  it  is  brighter  than  most  objects  of  its  class.  Tern- 
pel  and  Secchi  have  given  wonderful  descriptions  of  it, 
both  finding  multitudes  of  stars  intermingled  with  nebu- 
lous matter. 

For  a  last  glimpse  at  celestial  splendors  for  the  night, 
let  us  turn  to  the  rich  cluster  1630,  in  Argo,  just  above  the 
place  where  the  stream  of  the  Milky  Way — here  bright  in 
mid-channel  and  shallowing  toward  the  shores — separates 
into  two  or  three  currents  before  disappearing  behind  the 
horizon.  It  is  by  no  means  as  brilliant  as  some  of  the 
star  clusters  we  have  seen,  but  it  gains  in  beauty  and  im- 
pressiveness  from  the  presence  of  one  bright  star  that 
seems  to  captain  a  host  of  inferior  luminaries. 


CHAPTER    IV 

VIRGO   AND    HER   NEIGHBORS 

..."  that  region 
Where  still  by  night  is  seen 
The  Virgin  goddess  near  to  bright  Bo6tes." — POSTE'S  ARATUS. 

FOLLOWING  the  order  of  right  ascension,  we  come  next 
to  the  little  constellations  Crater  and  Corvus,  which  may 
be  described  as  standing  on  the  curves  of  Hydra  (map 
No.  8).  Beginning  with  Crater,  let  us  look  first  at  a,  a 
yellow  fourth-magnitude  star,  near  which  is  a  celebrated 
red  variable  R.  With  a  low  power  wre  can  see  both  a  and 
R  in  the  same  field  of  view,  like  a  very  wide  double. 
There  is  a  third  star  of  ninth  magnitude,  and  bluish  in 
color,  near  R  on  the  side  toward  a.  R  is  variable  both  in 
color  and  light.  When  reddest,  it  has  been  described  as 
"scarlet,"  "crimson,"  and  "blood-colored";  when  palest, 
it  is  a  deep  orange-red.  Its  light  variation  has  a  period 
the  precise  length  of  which  is  not  yet  known.  The  cycle 
of  change  is  included  between  the  eighth  and  ninth  mag- 
nitudes. 

While  our  three-inch  telescope  suffices  to  show  R,  it  is 
better  to  use  the  five-inch,  because  of  the  faintness  of  the 
star.  When  the  color  is  well  seen,  the  contrast  with  a  is 
very  pleasing. 

There  is  hardly  anything  else  in  Crater  to  interest  us, 
and  we  pass  over  the  border  into  Corvus,  and  go  at  once 
to  its  chief  attraction,  the  star  8.  The  components  of  this 
5  57 


VIRGO  AND  HER  NEIGHBORS  59 

beautiful  double  are  of  magnitudes  three  and  eight;  dis- 
tance 24",  p.  211°;  colors  yellow  and  purple. 

The  night  being  dark  and  clear,  we  take  the  five-inch 
and  turn  it  on  the  nebula  3128,  which  the  map  shows  just 
under  the  border  of  Corvus  in  the  edge  of  Hydra.  Her- 
schel  believed  he  had  resolved  this  into  stars.  It  is  a 
faint  object  and  small,  not  exceeding  one  eighth  of  the 
moon's  diameter. 

Farther  east  in  Hydra,  as  indicated  near  the  left-hand 
edge  of  map  No.  8,  is  a  somewhat  remarkable  variable, 
R  Hydra3.  This  star  occasionally  reaches  magnitude 
three  and  a  half,  while  at  minimum  it  is  not  much  above 
the  tenth  magnitude.  Its  period  is  about  four  hundred 
and  twenty-five  days. 

While  we  have  been  examining  these  comparatively 
barren  regions,  glad  to  find  one  or  two  colored  doubles 
to  relieve  the  monotony  of  the  search,  a  glittering  white 
star  has  frequently  drawn  our  eyes  eastward  and  upward. 
It  is  Spica,  the  great  gem  of  Virgo,  and,  yielding  to  its 
attraction,  we  now  enter  the  richer  constellation  over 
which  it  presides  (map  No.  9).  Except  for  its  beauty, 
which  every  one  must  admire,  Spica,  or  a  Virginis,  has 
no  special  claim  upon  our  attention.  Some  evidence  has 
been  obtained  that,  like  /3  Auriga3  and  Capella,  it  revolves 
with  an  invisible  companion  of  great  mass  in  an  orbit  only 
six  million  miles  in  diameter.  Spica's  spectrum  resembles 
that  of  Sirius.  The  faint  star  which  our  larger  apertures 
show  about  6'  northeast  of  Spica  is  of  the  tenth  mag- 
nitude. 

Sweeping  westward,  we  come  upon  2  1669,  a  pretty 
little  double  with  nearly  equal  components  of  about  the 
sixth  magnitude,  distance  5.6",  p.  124°.  But  our  interest 
is  not  fully  aroused  until  we  reach  7,  a  star  with  a  history. 
The  components  of  this  celebrated  binary  are  both  nearly 


60  PLEASURES  OF  THE  TELESCOPE 

of  the  third  magnitude,  distance  about  5.8",  p.  150°.  They 
revolve  around  their  common  center  in  something  less 
than  two  hundred  years.  According  to  some  authorities, 
the  period  is  one  hundred  and  seventy  years,  but  it  is  not 
yet  certainly  ascertained.  It  was  noticed  about  the  be- 
ginning of  the  seventeenth  century  that  7  Virginis  was 
double.  In  1836  the  stars  were  so  close  together  that  no 
telescope  then  in  existence  was  able  to  separate  them, 
although  it  is  said  that  the  disk  into  which  they  had 
merged  was  elongated  at  Pulkowa.  In  a  few  years  they 
became  easily  separable  once  more.  If  the  one-hundred- 
and-seventy-year  period  is  correct,  they  should  continue 
to  get  farther  apart  until  about  1921.  According  to 
Asaph  Hall,  their  greatest  apparent  distance  is  6.3",  and 
their  least  apparent  distance  0.5";  consequently,  they  will 
never  again  close  up  beyond  the  separating  power  of  ex- 
isting telescopes. 

There  is  a  great  charm  in  watching  this  pair  of  stars 
even  with  a  three-inch  telescope — not  so  much  on  account 
of  what  is  seen,  although  they  are  very  beautiful,  as  on 
account  of  what  we  know  they  are  doing.  It  is  no  slight 
thing  to  behold  two  distant  stars  obeying  the  law  that 
makes  a  stone  fall  to  the  ground  and  compels  the  earth 
to  swing  round  the  sun. 

In  6  we  discover  a  fine  triple,  magnitudes  four  and  a 
half,  nine,  and  ten;  distances  7",  p.  345°,  and  65",  p.  295°. 
The  ninth-magnitude  star  has  been  described  as  "  violet," 
but  such  designations  of  color  are  often  misleading  when 
the  star  is  very  faint.  On  the  other  hand  it  should  not 
be  assumed  that  a  certain  color  does  not  exist  because  the 
observer  can  not  perceive  it,  for  experience  shows  that 
there  is  a  wide  difference  among  observers  in  the  power 
of  the  eye  to  distinguish  color.  I  have  known  persons 
who  could  not  perceive  the  difference  of  hue  in  some  of 


62  PLEASURES  OF  THE  TELESCOPE 

the  most  beautifully  contrasted  colored  doubles  to  be 
found  in  the  sky.  I  am  acquainted  with  an  astronomer 
of  long  experience  in  the  use  of  telescopes,  whose  eye  is 
so  deficient  in  color  sense  that  he  d'enies  that  there  are 
any  decided  colors  amongftje'  stars.  Such  persons  miss 
one  of  the  finest  pleasures  of  the  telescope.  In  examining 
6  Virginis  we  shall  do  best  to  use  our  largest  aperture, 
viz.,  the  five-inch.  Yet  Webb  records  that  all  three  of  the 
stars  in  this  triple  have  been  seen  with  a  telescope  of  only 
three  inches  aperture.  The  amateur  must  remember  in 
such  cases  howT  much  depends  upon  practice  as  well  as 
upon  the  condition  of  the  atmosphere.  There  are  lamen- 
tably few  nights  in  a  year  when  even  the  best  telescope  is 
ideally  perfect  in  performance,  but  every  night's  obser- 
vation increases  the  capacity  of  the  eye,  begetting  a  kind 
of  critical  judgment  which  renders  it  to  some  extent  inde- 
pendent of  atmospheric  vagaries.  It  will  also  be  found 
that  the  idiosyncrasies  of  the  observer  are  reflected  in  his 
instrument,  wThich  seems  to  have  its  fits  of  excellence,  its 
inspirations  so  to  speak,  while  at  other  times  it  behaves 
as  if  all  its  wonderful  powers  had  departed. 

Another  double  that  perhaps  we  had  better  not  try 
with  less  than  four  inches  aperture  is  84  Virginis.  The 
magnitudes  are  six  and  nine;  distance,  3.5",  p.  233°.  Col- 
ors yellow  and  blue.  2  1846  is  a  fifth-magnitude  star 
with  a  tenth-magnitude  companion,  distance  only  4", 
p.  108°.  Use  the  five-inch. 

And  now  we  approach  something  that  is  truly  marvel- 
ous, the  "  Field  of  the  Nebula?."  This  strange  region, 
lying  mostly  in  the  constellation  Virgo,  is  roughly  out- 
lined by  the  stars  /3,  77,  7,  S,  and  e,  which  form  two  sides  of 
a  square  some  15°  across.  It  extends,  however,  for  some 
distance  into  Coma  Berenices,  while  outlying  nebula?  be- 
longing to  it  are  also  to  be  found  in  the  eastern  part  of 


VIRGO  AND  HER  NEIGHBORS  63 

Leo.  Unfortunately  for  those  who  expect  only  brilliant 
revelations  when  they  look  through  a  telescope,  this 
throng  of  nebula?  consists  of  small  and  inconspicuous 
wisps  as  ill  defined  as  bits  of  thistle-down  floating  high 
in  the  air.  There  are  more  than  three  hundred  of  them 
all  told,  but  even  the  brightest  are  faint  objects  when 
seen  with  the  largest  of  our  telescopes.  Why  do  they 
congregate  thus?  That  is  the  question  which  lends  an 
interest  to  the  assemblage  that  no  individual  member  of 
it  could  alone  command.  It  is  a  mystery,  but  beyond 
question  it  is  explicable.  The  explanation,  however,  is 
yet  to  be  discovered. 

The  places  of  only  three  of  the  nebula?  are  indicated  on 
the  map.  No.  2806  has  been  described  as  resembling  in 
shape  a  shuttle.  Its  length  is  nearly  one  third  of  the 
moon's  diameter.  It  is  brightest  near  the  center,  and  has 
several  faint  companions.  No.  2961  is  round,  ¥  in  diame- 
ter, and  is  accompanied  by  another  round  nebula  in  the 
same  field  of  view  toward  the  south.  No.  3105  is  double, 
and  powerful  telescopes  show  two  more  ghostly  compan- 
ions. There  is  an  opportunity  for  good  and  useful  work 
in  a  careful  study  of  the  little  nebula?  that  swim  into  view 
all  over  this  part  of  Virgo.  Celestial  photography  has 
triumphs  in  store  for  itself  here. 

Scattered  over  and  around  the  region  where  the  nebu- 
la? are  thickest  we  find  eight  or  nine  variable  stars,  three 
of  the  most  remarkable  of  which,  K,  S,  and  U,  may  be 
found  on  the  map.  R  is  very  irregular,  sometimes  attain- 
ing magnitude  six  and  a  half,  while  at  other  times  its 
maximum  brightness  does  not  exceed  that  of  an  eighth- 
magnitude  star.  At  minimum  it  sinks  to  the  tenth  or 
eleventh  magnitude.  Its  period  is  one  hundred  and  forty- 
five  days.  U  varies  from  magnitude  seven  or  eight  down 
to  magnitude  twelve  or  under  and  then  regains  its  light, 


64:  PLEASURES  OF  THE  TELESCOPE 

in  a  period  of  about  two  hundred  and  seven  days.  S  is 
interesting  for  its  brilliant  red  color.  When  brightest,  it 
exceeds  the  sixth  magnitude,  but  at  some  of  its  maxima 
the  magnitude  is  hardly  greater  'than  the  eighth.  At 
minimum  it  goes  below  the  twelfth  magnitude.  Period, 
three  hundred  and  seventy-six  days. 

Next  east  of  Virgo  is  Libra,  which  contains  a  few 
notable  objects  (map  No.  10).  The  star  a  has  a  fifth-mag- 
nitude companion,  distant  about  230",  which  can  be  easily 
seen  with  an  opera  glass.  At  the  point  marked  A  on  the 
map  is  a  curious  multiple  star,  sometimes  referred  to  by 
its  number  in  Piazzi's  catalogues  as  follows:  212  P.  xiv. 
The  two  principal  stars  are  easily  seen,  their  magnitudes 
being  six  and  seven  and  a  half;  distance  15",  p.  290°. 
Burnham  found  four  other  faint  companions,  for  which 
it  would  be  useless  for  us  to  look.  The  remarkable  thing 
is  that  these  faint  stars,  the  nearest  of  which  is  distant 
about  50"  from  the  largest  member  of  the  group  and  the 
farthest  about  129",  do  not  share,  according  to  their  dis- 
coverer, in  the  rapid  proper  motion  of  the  two  main  stars. 

In  i  we  find  a  double  a  little  difficult  for  our  three-inch. 
The  components  are  of  magnitudes  four  and  a  half  and 
nine,  distance  57",  p.  110°.  Burnham  discovered  that 
the  ninth-magnitude  star  consists  of  two  of  the  tenth  less 
than  2"  apart,  p.  24°. 

No  astronomer  who  happens  to  be  engaged  in  this  part 
of  the  sky  ever  fails,  unless  his  attention  is  absorbed  by 
something  of  special  interest,  to  glance  at  /?  Libra?,  which 
is  famous  as  the  only  naked-eye  star  having  a  decided 
green  color.  The  hue  is  pale,  but  manifest.* 

The  star  is  a  remarkable  variable,  belonging  to  what 
is  called  the  Algol  type.  Its  period,  according  to  Chan- 

*  Is  the  slight  green  tint  perceptible  in  Sirius  variable  ?    I  am  sometimes  dis- 
posed to  think  it  is. 


66  PLEASURES  OF  THE  TELESCOPE 

dler,  is  2  days  7  hours,  51  minutes,  22.8  seconds.  The  time 
occupied  by  the  actual  changes  is  about  twelve  hours.  At 
maximum  the  star  is  of  magnitude  five  and  at  minimum  of 
magnitude  6.2. 

We  may  now  conveniently  turn  northward  from  Virgo 
in  order  to  explore  Bootes,  one  of  the  most  interesting  of 
the  constellations  (map  No.  11).  Its  leading  star  a,  Arctu- 
rus,  is  the  brightest  in  the  northern  hemisphere.  Its  pre- 
cedence over  its  rivals  Vega  and  Capella,  long  in  dispute, 
has  been  settled  by  the  Harvard  photometry.  You  notice 
that  the  color  of  Arcturus,  when  it  has  not  risen  far  above 
the  horizon,  is  a  yellowish  red,  but  when  the  star  is  near 
mid-heaven  the  color  fades  to  light  yellow.  The  hue  is 
possibly  variable,  for  it  is  recorded  that  in  1852  Arctu- 
rus appeared  to  have  nearly  lost  its  color.  If  it  should 
eventually  turn  white,  the  fact  would  have  an  important 
bearing  upon  the  question  whether  Sirius  was,  as  alleged, 
once  a  red  or  flame-colored  star. 

But  let  us  sit  here  in  the  starlight,  for  the  night  is 
balmy,  and  talk  about  Arcturus,  which  is  perhaps  actually 
the  greatest  sun  within  the  range  of  terrestrial  vision. 
Its  parallax  is  so  minute  that  the  consideration  of  the 
tremendous  size  of  this  star  is  a  thing  that  the  imagina- 
tion can  not  placidly  approach.  Calculations,  based  on 
its  assumed  distance,  which  show  that  it  outshines  the  sun 
several  thousand  times,  may  be  no  exaggeration  of  the  truth! 
It  is  easy  to  make  such  a  calculation.  One  of  Dr.  Elkin's 
parallaxes  for  Arcturus  is  0.018".  That  is  to  say,  the  dis- 
placement of  Arcturus  due  to  the  change  in  the  observer's 
point  of  view  when  he  looks  at  the  star  first  from  one 
side  and  then  from  the  other  side  of  the  earth's  orbit, 
186,000,000  miles  across,  amounts  to  only  eighteen  one- 
thousandths  of  a  second  of  arc.  We  can  appreciate  how 
small  that  is  when  we  reflect  that  it  is  about  equal  to  the 


,A    MAJOR 


RONA    BOREALIS 


SERPENS 


:ANES  VENATICI 


MAP  No.  11. 


68  PLEASURES  OF  THE  TELESCOPE 

apparent  distance  between  the  heads  of  two  pins  placed 
an  inch  apart  and  viewed  from  a  distance  of  a  hundred 
and  eighty  miles! 

Assuming  this  estimate  of  the  parallax  of  Arcturus, 
let  us  see  how  it  will  enable  us  to  calculate  the  probable 
size  or  light-giving  power  of  the  star  as  compared  with  the 
sun.  The  first  thing  to  do  is  to  multiply  the  earth's  dis- 
tance from  the  sun,  which  may  be  taken  at  93,000,000 
miles,  by  206,265,  the  number  of  seconds  of  arc  in  a  radian, 
the  base  of  circular  measure,  and  then  divide  the  product 
by  the  parallax  of  the  star.  Performing  the  multiplica- 
tion and  division,  we  get  the  following: 

19,182,645,000,000  _  1)065>790>250)000>000. 

The  quotient  represents  miles!  Call  it,  in  round  numbers, 
a  thousand  millions  of  millions  of  miles.  This  is  about 
11,400,000  times  the  distance  from  the  earth  to  the  sun. 

Now  for  the  second  part  of  the  calculation:  The 
amount  of  light  received  on  the  earth  from  some  of  the 
brighter  stars  has  been  experimentally  compared  writh  the 
amount  received  from  the  sun.  The  results  differ  rather 
widely,  but  in  the  case  of  Arcturus  the  ratio  of  the  star's 
light  to  sunlight  may  be  taken  as  about  one  twenty-five- 
thousand-millionth— i.  e.,  25,000,000,000  stars,  each  equal 
to  Arcturus,  would  together  shed  upon  the  earth  as  much 
light  as  the  sun  does.  But  we  know  that  light  varies  in- 
versely as  the  square  of  the  distance;  for  instance,  if  the 
sun  were  twice  as  far  away  as  it  is,  its  light  would  be 
diminished  for  us  to  a  quarter  of  its  present  amount. 
Suppose,  then,  that  we  could  remove  the  earth  to  a  point 
midway  between  the  sun  and  Arcturus,  we  should  then 
be  5,700,000  times  as  far  from  the  sun  as  we  now  are.  In 
order  to  estimate  how  much  light  the  sun  would  send  us 
from  that  distance  we  must  square  the  number  5,700,000 


VIRGO  AND  HER  NEIGHBORS  69 

and  then  take  the  result  inversely,  or  as  a  fraction.     We 

thUS  get  32,490,000,000,000,  rePresepting  the  ratio  of  the 
sun's  light  at  half  the  distance  of  Arcturus  to  that  at  its 
real  distance.  But  while  receding  from  the  sun  we  should 
be  approaching  Arcturus.  We  should  get,  in  fact,  twice 
as  near  to  that  star  as  we  were  before,  and  therefore  its 
light  would  be  increased  for  us  fourfold.  Now,  if  the 
amount  of  sunlight  had  not  changed,  it  would  exceed  the 
light  of  Arcturus  only  a  quarter  as  much  as  it  did  before, 

or  in  the  ratio  of  25'000'0°0'000  =  6,250,000,000  to  1.     But, 

as  we  have  seen,  the  sunlight  would  diminish  through  in- 
crease of  distance  to  one  32,490,000,000,000th  part  of  its 
original  amount.  Hence  its  altered  ratio  to  the  light  of 
Arcturus  would  become  6,250,000,000  to  32,490,000,000,000, 
or  1  to  5,198. 

This  means  that  if  the  earth  were  situated  midway 
between  the  sun  and  Arcturus,  it  would  receive  5,198 
times  as  much,  light  from  that  star  as  it  would  from  the 
sun!  It  is  quite  probable,  moreover,  that  the  heat  of 
Arcturus  exceeds  the  solar  heat  in  the  same  ratio,  for 
the  spectroscope  shows  that  although  Arcturus  is  sur- 
rounded with  a  cloak  of  metallic  vapors  proportionately 
far  more  extensive  than  the  sun's,  yet,  smothered  as  the 
great  star  seems  in  some  respects  to  be,  it  rivals  Sirius 
itself  in  the  intensity  of  its  radiant  energy. 

If  we  suppose  the  radiation  of  Arcturus  to  be  the  same 
per  unit  of  surface  as  the  sun's,  it  follows  that  Arcturus 
exceeds  the  sun  about  375,000  times  in  volume,  and  that 
its  diameter  is  no  less  than  62,350,000  miles!  Imagine  the 
earth  and  the  other  planets  constituting  the  solar  system 
removed  to  Arcturus  and  set  revolving  around  it  in  orbits 
of  the  same  forms  and  sizes  as  those  in  which  they  circle 


70  PLEASURES  OF  THE  TELESCOPE 

about  the  sun.  Poor  Mercury!  For  that  little  planet  it 
would  indeed  be  a  jump  from  the  frying  pan  into  the  fire, 
because,  as  it  rushed  to  perihelion,  Mercury  would  plunge 
more  than  2,500,000  miles  beneath  the  surface  of  the  giant 
star.  Venus  and  the  earth  would  melt  like  snowflakes 
at  the  mouth  of  a  furnace.  Even  far-away  Neptune,  the 
remotest  member  of  the  system,  would  swelter  in  torrid 
heat. 

But  stop!  Look  at  the  sky.  Observe  how  small  and 
motionless  the  disks  of  the  stars  have  become.  Back  to 
the  telescopes  at  once,  for  this  is  a  token  that  the  atmos- 
phere is  steady,  and  that  "  good  seeing "  may  be  ex- 
pected. It  is  fortunate,  for  we  have  some  delicate  work 
before  us.  The  very  first  double  star  we  try  in  Bootes,  X 
1772,  requires  the  use  of  the  four-inch,  and  the  five-inch 
shows  it  more  satisfactorily.  The  magnitudes  are  sixth 
and  ninth,  distance  5",  p.  140°.  On  the  other  side  of  Arc- 
turus  we  find  f,  a  star  that  we  should  have  had  no  great 
difficulty  in  separating  thirty  years  ago,  but  which  has 
now  closed  up  beyond  the  reach  even  of  our  five-inch. 
The  magnitudes  are  both  fourth,  and  the  distance  less  than 
a  quarter  of  a  second;  position  angle  changing.  It  is  ap- 
parently a  binary,  and  if  so  will  some  time  widen  again, 
but  its  period  is  unknown.  The  star  279,  also  known  as  5 
1910,  near  the  southeastern  edge  of  the  constellation,  is  a 
pretty  double,  each  component  being  of  the  seventh  mag- 
nitude, distance  4",  p.  212°.  Just  above  f  we  come  upon 
TT,  an  easy  double  for  the  three-inch,  magnitudes  four  and 
six,  distance  6"  p.  99°.  Next  is  f,  a  yellow  and  purple 
pair,  whose  magnitudes  are  respectively  five  and  seven, 
distance  less  than  3",  p.  200°.  This  is  undoubtedly  a  bi- 
nary with  a  period  of  revolution  of  about  a  hundred  and 
thirty  years.  Its  distance  decreased  about  V  between 
1881  and  1891.  It  was  still  decreasing  in  1899,  when  it 


VIRGO  AND  HER  NEIGHBORS  71 

had  become  2.5".  The  orbital  swing  is  also  very  apparent 
in  the  change  of  the  position  angle. 

The  telescopic  gem  of  Bootes,  and  one  of  "  the  flowers 
of  the  sky,"  is  e,  also  known  as  Mirac.  When  well  seen, 
as  we  shall  see  it  to-night,  e  Bootis  is  superb.  The  mag- 
nitudes of  its  two  component  stars  are  two  and  a  half  (ac- 
cording to  Hall,  three)  and  six.  The  distance  is  about 
2.8",  p.  326°.  The  contrast  of  colors— bright  orange 
yellow,  set  against  brilliant  emerald  green — is  mag- 
nificent. There  are  very  few  doubles  that  can  be  com- 
pared with  it  in  this  respect.  The  three-inch  will  sepa- 
rate it,  but  the  five-inch  enables  us  best  to  enjoy  its 
beauty.  It  appears  to  be  a  binary,  but  the  motion  is  very 
slow,  and  nothing  certain  is  yet  known  of  its  period. 

In  8  we  have  a  very  wide  and  easy  double;  magnitudes 
three  and  a  half  and  eight  and  a  half,  distance  110",  p. 
75°.  The  smaller  star  has  a  lilac  hue.  We  can  not  hope 
with  any  of  our  instruments  to  see  all  of  the  three  stars 
contained  in  /*,  but  two  of  them  are  easily  seen;  magni- 
tudes four  and  seven,  distance  108",  p.  172°.  The  smaller 
star  is  again  double;  magnitudes  seven  and  eight,  dis- 
tance 0.77",  p.  88°.  It  is  clearly  a  binary,  with  a  long 
period.  A  six-inch  telescope  that  could  separate  this  star 
at  present  would  be  indeed  a  treasure.  %  1926  is  another 
object  rather  beyond  our  powers,  on  account  of  the  con- 
trast of  magnitudes.  These  are  six  and  eight  and  a  half; 
distance  1.3",  p.  256°. 

Other  doubles  are:  44  (21909),  magnitudes  five  and 
six,  distance  4.8",  p.  240°;  39  (£1890),  magnitudes  both 
nearly  six,  distance  3.6",  p.  45°.  Smaller  star  light  red;  t, 
magnitudes  four  and  a  half  and  seven  and  a  half,  distance 
38",  p.  33°;  *,  magnitudes  five  and  a  half  and  eight,  dis- 
tance 12.7",  p.  238°.  Some  observers  see  a  greenish  tinge 
in  the  light  of  the  larger  star,  the  smaller  one  being  blue. 


72  PLEASURES  OF  THE  TELESCOPE 

There  are  one  or  two  interesting  things  to  be  seen  in 
that  part  of  Canes  Venatici  which  is  represented  on  map 
No.  11.  The  first  of  these  is  the  star  cluster  3936.  This 
will  reward  a  good  look  with  the  five-inch.  With  large 
telescopes  as  many  as  one  thousand  stars  have  been  dis- 
cerned packed  within  its  globular  outlines. 

The  star  25  (2  1768)  is  a  close  binary  with  a  period 
estimated  at  one  hundred  and  twenty-five  years.  The 
magnitudes  are  six  and  seven  or  eight,  distance  about  1", 
p.  137°.  We  may  try  for  this  with  the  five-inch,  and  if  we 
do  not  succeed  in  separating  the  stars  we  may  hope  to  do 
so  some  time,  for  the  distance  between  them  is  increasing. 

Although  the  nebula  3572  is  a  very  wonderful  object, 
we  shall  leave  it  for  another  evening. 

Eastward  from  Bootes  shines  the  circlet  of  Corona 
Borealis,  whose  form  is  so  strikingly  marked  out  by  the 
stars  that  the  most  careless  eye  perceives  it  at  once. 
Although  a  very  small  constellation,  it  abounds  with  in- 
teresting objects.  We  begin  our  attack  with  the  five-inch 
on  S  1932,  but  not  too  confident  that  we  shall  come  off 
victors,  for  this  binary  has  been  slowly  closing  for  many 
years.  The  magnitudes  are  six  and  a  half  and  seven,  dis- 
tance 0.84",  p.  150°.  Not  far  distant  is  another  binary,  at 
present  beyond  our  powers,  rj.  Here  the  magnitudes  are 
both  six,  distance  0.65",  p.  3°.  Hall  assigns  a  period  of 
forty  years  to  this  star. 

The  assemblage  of  close  binaries  in  this  neighborhood 
is  very  curious.  Only  a  few  degrees  away  we  find  one 
that  is  still  more  remarkable,  the  star  7.  What  has  previ- 
ously been  said  about  42  Coma?  Berenicis  applies  in  a 
measure  to  this  star  also.  It,  too,  has  a  comparatively 
small  orbit,  and  its  components  are  never  seen  widely 
separated.  In  1826  their  distance  was  0.7";  in  1880  they 
could  not  be  split;  in  1891  the  distance  had  increased  to 


VIRGO  AND  HER  NEIGHBORS  73 

0.36",  and  in  1894  it  had  become  0.53",  p.  123°.  But  in 
1899  Lewis  made  the  distance  only  0.43".  The  period  has 
been  estimated  at  one  hundred  years. 

While  the  group  of  double  stars  in  the  southern  part 
of  Corona  Borealis  consists,  as  we  have  seen,  of  remark- 
ably close  binaries,  another  group  in  the  northern  part  of 
the  same  constellation  comprises  stars  that  are  easily 
separated.  Let  us  first  try  ?.  The  powers  of  the  three- 
inch  are  amply  sufficient  in  this  case.  The  magnitudes 
are  four  and  five,  distance  6.3",  p.  300°.  Colors,  white  or 
bluish-white  and  blue  or  green. 

Next  take  cr?  whose  magnitudes  are  five  and  six,  dis- 
tance 4",  p.  206°.  With  the  five-inch  we  may  look  for  a 
second  companion  of  the  tenth  magnitude,  distance  54", 
p.  88°.  It  is  thought  highly  probable  that  <r  is  a  binary, 
but  its  period  has  simply  been  guessed  at. 

Finally,  we  come  to  z/,  which  consists  of  two  very 
widely  separated  stars,  v1  and  i>2,  each  of  which  has  a  faint 
companion.  With  the  five-inch  we  may  be  able  to  see  the 
companion  of  z>2,  the  more  southerly  of  the  pair.  The 
magnitude  of  the  companion  is  variously  given  as  tenth 
and  twelfth,  distance  137",  p.  18°. 

With  the  aid  of  the  map  we  find  the  position  of  the 
new  star  of  1866,  which  is  famous  as  the  first  so-called 
temporary  star  to  which  spectroscopic  analysis  was  ap- 
plied. When  first  noticed,  on  May  12,  1866,  this  star  was 
of  the  second  magnitude,  fully  equaling  in  brilliancy  a, 
the  brightest  star  of  the  constellation;  but  in  about  two 
weeks  it  fell  to  the  ninth  magnitude.  Huggins  and  Mil- 
ler eagerly  studied  the  star  with  the  spectroscope,  and 
their  results  were  received  with  deepest  interest.  They 
concluded  that  the  light  of  the  new  star  had  two  different 
sources,  each  giving  a  spectrum  peculiar  to  itself.  One  of 
the  spectra  had  dark  lines  and  the  other  bright  lines.  It 
6 


74  PLEASURES  OF  THE  TELESCOPE 

will  be  remembered  that  a  similar  peculiarity  was  exhib- 
ited by  the  new  star  in  Auriga  in  1893.  But  the  star  in 
Corona  did  not  disappear.  It  diminished  to  magnitude 
nine  and  a  half  or  ten,  and  stopped 'there;  and  it  is  still 
visible.  In  fact,  subsequent  examination  proved  that  it 
had  been  catalogued  at  Bonn  as  a  star  of  magnitude  nine 
and  a  half  in  1855.  Consequently  this  "  blaze  star  "  of 
1866  will  bear  watching  in  its  decrepitude.  Nobody 
knows  but  that  it  may  blaze  again.  Perhaps  it  is  a  sun- 
like  body;  perhaps  it  bears  little  resemblance  to  a  sun 
as  we  understand  such  a  thing.  But  whatever  it  may  be, 
it  has  proved  itself  capable  of  doing  very  extraordinary 
things. 

We  have  no  reason  to  suspect  the  sun  of  any  latent 
eccentricities,  like  those  that  have  been  displayed  by 
"temporary"  stars;  yet,  acting  on  the  principle  which 
led  the  old  emperor-astrologer  Rudolph  II  to  torment  his 
mind  with  self-made  horoscopes  of  evil  import,  let  us  un- 
scientifically imagine  that  the  sun  could  suddenly  burst 
out  with  several  hundred  times  its  ordinary  amount  of 
heat  and  light,  thereby  putting  us  into  a  proper  condition 
for  spectroscopic  examination  by  curious  astronomers  in 
distant  worlds. 

But  no,  after  all,  it  is  far  pleasanter  to  keep  within 
the  strict  boundaries  of  science,  and  not  imagine  anything 
of  the  kind. 


CHAPTER    V 

IN    SUMMER    STAR-LANDS. 

"  I  heard  the  trailing  garments  of  the  night 

Sweep  through  her  marble  halls, 
I  saw  her  sable  skirts  all  fringed  with  light 

From  the  celestial  walls. " — H.  W.  LONGFELLOW. 

IN  the  soft  air  of  a  summer  night,  when  fireflies  are 
flashing  their  lanterns  over  the  fields,  the  stars  do  not 
sparkle  and  blaze  like  those  that  pierce  the  frosty  skies  of 
winter.  The  light  of  Sirius,  Aldebaran,  Rigel,  and  other 
midwinter  brilliants  possesses  a  certain  gemlike  hardness 
and  cutting  quality,  but  Antares  and  Vega,  the  great 
summer  stars,  and  Arcturus,  when  he  hangs  westering  in 
a  July  night,  exhibit  a  milder  radiance,  harmonizing  with 
the  character  of  the  season.  This  difference  is,  of  course, 
atmospheric  in  origin,  although  it  may  be  partly  subjec- 
tive, depending  upon  the  mental  influences  of  the  muta- 
tions of  Nature. 

The  constellation  Scorpio  is  nearly  as  striking  in  out- 
line as  Orion,  and  its  brightest  star,  the  red  Antares  (a  in 
map  No.  12),  carries  concealed  in  its  rays  a  green  jewel 
which,  to  the  eye  of  the  enthusiast  in  telescopic  recrea- 
tion, appears  more  beautiful  and  inviting  each  time  that 
he  penetrates  to  its  hiding  place. 

We  shall  begin  our  night's  work  with  this  object,  and 
the  four-inch  glass  will  serve  our  purpose,  although  the 
untrained  observer  would  be  more  certain  of  success  with 

75 


76  PLEASURES  OF  THE  TELESCOPE 

the  five-inch.  A  friend  of  mine  has  seen  the  companion 
of  Antares  with  a  three-inch,  but  I  have  never  tried  the 
star  with  so  small  an  aperture.  When  the  air  is  steady 
and  the  companion  can  be  well  viewed,  there  is  no  finer 
sight  among  the  double  stars.  The  contrast  of  colors  is 
beautifully  distinct — fire-red  and  bright  green.  The  little 
green  star  has  been  seen  emerging  from  behind  the  moon, 
ahead  of  its  ruddy  companion.  The  magnitudes  are  one 
and  seven  and  a  half  or  eight,  distance  3",  p.  270°.  An- 
tares is  probably  a  binary,  although  its  binary  character 
has  not  yet  been  established. 

A  slight  turn  of  the  telescope  tube  brings  us  to  the 
star  (7,  a  wide  double,  the  smaller  component  of  which  is 
blue  or  plum-colored;  magnitudes  four  and  nine,  distance 
20",  p.  272°.  From  <r  we  pass  to  /?,  a  very  beautiful  object, 
of  which  the  three-inch  gives  us  a  splendid  view.  Its  two 
components  are  of  magnitudes  two  and  six,  distance  13", 
p.  30°;  colors,  white  and  bluish.  It  is  interesting  to  know 
that  the  larger  star  is  itself  double,  although  none  of  the 
telescopes  we  are  using  can  split  it.  Burnham  discovered 
that  it  has  a  tenth-magnitude  companion;  distance  less 
than  1",  p.  87°. 

And  now  for  a  triple,  which  will  probably  require  the 
use  of  our  largest  glass.  Up  near  the  end  of  the  northern 
prolongation  of  the  constellation  we  perceive  the  star  f. 
The  three-inch  shows  us  that  it  is  double;  the  five-inch 
divides  the  larger  star  again.  The  magnitudes  are  respec- 
tively five,  five  and  a  half,  and  seven  and  a  half,  distances 
0.94",  p.  215°,  and  7",  p.  70°. 

A  still  more  remarkable  star,  although  one  of  its  com- 
ponents is  beyond  our  reach,  is  v.  With  the  slightest 
magnifying  this  object  splits  up  into  two  stars,  of  magni- 
tudes four  and  seven,  situated  rather  more  than  40"  apart. 
A  high  power  divides  the  seventh-magnitude  companion 


78  PLEASURES  OF  THE  TELESCOPE 

into  two,  each  of  magnitude  six  and  a  half,  distance  1.8", 
p.  42°.  But  (and  this  was  another  of  Burnham's  discover- 
ies) the  fourth-magnitude  star  itself  is  double,  distance 
0.8",  p.  about  0°.  The  companion  in  this  case  is  of  mag- 
nitude five  and  a  half. 

Next  we  shall  need  a  rather  low-power  eyepiece  and 
our  largest  aperture  in  order  to  examine  a  star  cluster, 
No.  4173,  which  was  especially  admired  by  Sir  William 
Herschel,  who  discovered  that  it  was  not,  as  Messier  had 
supposed,  a  circular  nebula.  Herschel  regarded  it  as  the 
richest  mass  of  stars  in  the  firmament,  but  with  a  small 
telescope  it  appears  merely  as  a  filmy  speck  that  has 
sometimes  been  mistaken  for  a  comet.  In  1860  a  new 
star,  between  the  sixth  and  seventh  magnitude  in  bril- 
liance, suddenly  appeared  directly  in  or  upon  the  cluster, 
and  the  feeble  radiance  of  the  latter  was  almost  extin- 
guished by  the  superior  light  of  the  stranger.  The  latter 
disappeared  in  less  than  a  month,  and  has  not  been  seen 
again,  although  it  is  suspected  to  be  a  variable,  and,  as 
such,  has  been  designated  with  the  letter  T.  Two  other 
known  variables,  both  very  faint,  exist  in  the  immediate 
neighborhood.  According  to  the  opinion  that  was  for- 
merly looked  upon  with  favor,  the  variable  T,  if  it  is 
a  variable,  simply  lies  in  the  line  of  sight  between  the 
earth  and  the  star  cluster,  and  has  no  actual  connection 
with  the  latter.  But  this  opinion  may  not,  after  all,  be 
correct,  for  Mr.  Bailey's  observations  show  that  variable 
stars  sometimes  exist  in  large  numbers  in  clusters,  al- 
though the  variables  thus  observed  are  of  short  period. 
The  cluster  4183,  just  west  of  Antares,  is  also  worth  a 
glance  with  the  five-inch  glass.  It  is  dense,  but  its  stars 
are  very  small,  so  that  to  enjoy  its  beauty  we  should  have 
to  employ  a  large  telescope.  Yet  there  is  a  certain  attrac- 
tion in  these  far-away  glimpses  of  starry  swarms,  for  they 


IN  SUMMER  STAR-LANDS  79 

give  us  some  perception  of  the  awful  profundity  of  space. 
When  the  mind  is  rightly  attuned  for  these  revelations 
of  the  telescope,  there  are  no  words  that  can  express  its 
impressions  of  the  overwhelming  perspective  of  the  uni- 
verse. 

The  southern  part  of  the  constellation  Ophiuchus  is 
almost  inextricably  mingled  with  Scorpio.  We  shall, 
therefore,  look  next  at  its  attractions,  beginning  with  the 
remarkable  array  of  star  clusters  4264,  4268,  4269,  and 
4270.  All  of  these  are  small,  2'  or  3'  in  diameter,  and 
globular  in  shape.  No.  4264  is  the  largest,  and  we  can 
see  some  of  the  stars  composing  it.  But  these  clusters, 
like  those  just  described  in  Scorpio,  are  more  interesting 
for  what  they  signify  than  for  what  they  show;  and  the 
interest  is  not  diminished  by  the  fact  that  their  meaning 
is  more  or  less  of  a  mystery.  Whether  they  are  composed 
of  pygmy  suns  or  of  great  solar  globes  like  that  one  which 
makes  daylight  for  the  earth,  their  association  in  spher- 
ical groups  is  equally  suggestive. 

'There  are  two  other  star  clusters  in  Ophiuchus,  and 
within  the  limits  of  map  No.  12,  both  of  which  are  more 
extensive  than  those  we  have  just  been  looking  at.  No. 
4211  is  5'  or  6'  in  diameter,  also  globular,  brighter  at  the 
center,  and  surrounded  by  several  comparatively  con- 
spicuous stars.  No.  4346  is  still  larger,  about  half  as 
broad  as  the  moon,  and  many  of  its  scattered  stars  are  of 
not  less  than  the  ninth  magnitude.  With  a  low  mag- 
nifying power  the  field  of  view  surrounding  the  cluster 
appears  powdered  with  stars. 

There  are  only  two  noteworthy  doubles  in  that  part  of 
Ophiuchus  with  which  we  are  at  present  concerned:  36, 
whose  magnitudes  are  five  and  seven,  distance  4.3",  p. 
195°,  colors  yellow  and  red;  and  39,  magnitudes  six  and 
seven  and  a  half,  distance  12",  p.  356°,  colors  yellow  or 


80  PLEASURES  OF  THE  TELESCOPE 

orange  and  blue.  The  first  named  is  a  binary  whose 
period  has  not  been  definitely  ascertained. 

The  variable  R  has  a  period  a  little  less  than  three  hun- 
dred and  three  days.  At  its  brightest  it  is  of  magnitude 
seven  or  eight,  and  at  minimum  it  diminishes  to  about  the 
twelfth  magnitude. 

The  spot  where  the  new  star  of  1604  appeared  is  indi- 
c^ated  on  the  map.  This  was,  with  the  exception  of 
Tycho's  star  in  1572,  the  brightest  temporary  star  of 
which  we  possess  a  trustworthy  account.  It  is  frequently 
referred  to  as  Kepler's  star,  because  Kepler  watched  it 
with  considerable  attention,  but  unfortunately  he  was  not 
as  good  an  observer  as  Tycho  was.  The  star  was  first 
seen  on  October  10,  1604,  and  was  then  brighter  than 
Jupiter.  It  did  not,  however,  equal  Venus.  It  gradually 
faded  and  in  March,  1606,  disappeared.  About  twelve  de- 
grees northwest  of  the  place  of  the  star  of  1604,  and  in 
that  part  of  the  constellation  Serpens  which  is  included 
in  map  No.  12,  we  find  the  location  of  another  temporary 
star,  that  of  1848.  It  was  first  noticed  by  Mr.  Hind  on 
April  28th  of  that  year,  when  its  magnitude  was  not  much 
above  the  seventh,  and  its  color  was  red.  It  brightened 
rapidly,  until  on  May  2d  it  was  of  magnitude  three  and  a 
half.  Then  it  began  to  fade,  but  very  slowly,  and  it  has 
never  entirely  disappeared.  It  is  now  of  the  twelfth  or 
thirteenth  magnitude. 

In  passing  we  may  glance  with  a  low  power  at  v  Ser- 
pentis,  a  wide  double,  magnitudes  four  and  nine,  distance 
50",  p.  31°,  colors  contrasted  but  uncertain. 

Sagittarius  and  its  neighbor,  the  small  but  rich  constel- 
lation Scutum  Sobieskii,  attract  us  next.  We  shall  first 
deal  with  the  western  portions  of  these  constellations 
which  are  represented  on  Map  No.  12.  The  star  /*  in  Sa- 
gittarius is  a  wide  triple,  magnitudes  three  and  a  half, 


IN  SUMMER  STAR-LANDS  81 

nine  and  a  half,  and  ten,  distances  40",  p.  315°,  and  45",  p. 
114°.  But  the  chief  glory  of  Sagittarius  (and  the  same 
statement  applies  to  Scutum  Sobieskii)  lies  in  its  assem- 
blage of  star  clusters.  One  of  these,  No.  4361,  also  known 
as  M  8,  is  plainly  visible  to  the  naked  eye  as  a  bright  spot 
in  the  Milky  Way.  We  turn  our  five-inch  telescope,  armed 
with  a  low  magnifying  power,  upon  this  subject  and  enjoy 
a  rare  spectacle.  As  we  allow  it  to  drift  through  the  field 
we  see  a  group  of  three  comparatively  brilliant  stars 
advancing  at  the  front  of  a  wonderful  train  of  mingled 
star  clusters  and  nebulous  clouds.  A  little  northwest  of 
it  appea'rs  the  celebrated  trifid  nebula,  No.  4355  on  the 
map.  There  is  some  evidence  that  changes  have  occurred 
in  this  nebula  since  its  discovery  in  the  last  century.  Bar- 
nard has  made  a  beautiful  photograph  showing  M  8  and 
the  trifid  nebula  on  the  same  plate,  and  he  remarks  that 
the  former  is  a  far  more  remarkable  object  than, its  more 
famous  neighbor.  Near  the  eastern  border  of  the  princi- 
pal nebulous  cloud  there  is  a  small  and  very  black  hole 
with  a  star  poised  on  its  eastern  edge.  This  hole  and  the 
star  are  clearly  shown  in  the  photograph. 

Cluster  No.  4397  (M  24)  is  usually  described  as  resem- 
bling, to  the  naked  eye,  a  protuberance  on  the  edge  of  the 
Milky  Way.  It  is  nearly  three  times  as  broad  as  the 
moon,  and  is  very  rich  in  minute  stars,  which  are  at  just 
such  a  degree  of  visibility  that  crowds  of  them  continually 
appear  and  disappear  while  the  eye  wanders  over  the  field, 
just  as  faces  are  seen  and  lost  in  a  vast  assemblage  of 
people.  This  kind  of  luminous  agitation  is  not  peculiar 
to  M  24,  although  that  cluster  exhibits  it  better  than  most 
others  do  on  account  of  both  the  multitude  and  the  mi- 
nuteness of  its  stars. 

A  slight  sweep  eastward  brings  us  to  yet  another  meet- 
ing place  of  stars,  the  cluster  M  25,  situated  between  the 


82  PLEASURES  OF  THE  TELESCOPE 

variables  U  and  V.  This  is  brilliant  and  easily  resolved 
into  its  components,  which  include  a  number  of  double 
stars. 

The  two  neighboring  variables  just  referred  to  are 
interesting.  U  has  a  period  of  about  six  days  and  three 
quarters,  and  its  range  of  magnitude  runs  from  the 
seventh  down  to  below  the  eighth.  V  is  a  somewhat  mys- 
terious star.  Chandler  removed  it  from  his  catalogue  of 
variables  because  no  change  had  been  observed  in  its  light 
by  either  himself,  Sawyer,  or  Yendell.  Quirling,  the  dis- 
coverer of  its  variability,  gave  the  range  as  between  mag- 
nitudes 7.6  and  8.8.  It  must,  therefore,  be  exceedingly 
erratic  in  its  changes,  resembling  rather  the  temporary 
stars  than  the  true  variables. 

In  that  part  of  Scutum  Sobieskii  contained  in  map 
No.  12  we  find  an  interesting  double,  2  2325,  whose  magni- 
tudes are  six  and  nine,  distance  12.3",  p.  260°,  colors  white 
and  orange.  S  2306  is  a  triple,  magnitudes  seven,  eight, 
and  nine,  distances  12",  p.  220°,  and  0.8",  p.  68°.  The 
third  star  is,  however,  beyond  our  reach.  The  colors  of 
the  two  larger  are  respectively  yellow  and  violet. 

The  star  cluster  4400  is  about  one  quarter  as  broad 
as  the  moon,  and  easily  seen  with  our  smallest  aperture. 

Passing  near  to  the  region  covered  by  map  No.  13,  we 
find  the  remaining  portions  of  the  constellations  Sagitta- 
rius and  Scutum  Sobieskii.  It  will  be  advisable  to  finish 
with  the  latter  first.  Glance  at  the  clusters  4426  and 
4437.  Neither  is  large,  but  both  are  rich  in  stars.  The 
nebula  4441  is  a  fine  object  of  its  kind.  It  brightens  to- 
ward the  center,  and  Herschel  thought  he  had  resolved  it 
into  stars.  The  variable  R  is  remarkable  for  its  eccen- 
tricities. Sometimes  it  attains  nearly  the  fourth  magni- 
tude, although  usually  at  maximum  it  is  below  the  fifth, 
while  at  minimum  it  is  occasionally  of  the  sixth  and  at 


84  PLEASURES  OF  THE  TELESCOPE 

other  times  of  the  seventh  or  eighth  magnitude.  Its 
period  is  irregular. 

Turning  back  to  Sagittarius,  we  resume  our  search  for 
interesting  objects  there,  and  the  frst  that  we  discover  is 
another  star  cluster,  for  the  stars  are  wonderfully  grega- 
rious in  this  quarter  of  the  heavens.  The  number  our 
cluster  bears  on  the  map  is  4424,  corresponding  with  M  22 
in  Messier's  catalogue.  It  is  very  bright,  containing 
many  stars  of  the  tenth  and  eleventh  magnitudes,  as  well 
as  a  swarm  of  smaller  ones.  Sir  John  Herschel  regarded 
the  larger  stars  in  this  cluster  as  possessing  a  reddish 
tint.  Possibly  there  was  some  peculiarity  in  his  eye  that 
gave  him  this  impression,  for  he  has  described  a  cluster 
in  the  constellation  Toucan  in  the  southern  hemisphere  as 
containing  a  globular  mass  of  rose-colored  stars  inclosed 
in  a  spherical  shell  of  white  stars.  Later  observers  have 
confirmed  his  description  of  the  shape  and  richness  of  this 
cluster  in  Toucan,  but  have  been  unable  to  perceive  the 
red  hue  of  the  interior  stars. 

The  eastern  expanse  of  Sagittarius  is  a  poor  region 
compared  with  the  western  end  of  the  constellation, 
where  the  wide  stream  of  the  Milky  Way  like  a  great  river 
enriches  its  surroundings.  The  variables  T  and  R  are  of 
little  interest  to  us,  for  they  never  become  bright  enough 
to  be  seen  without  the  aid  of  a  telescope.  In  54  we  find, 
however,  an  interesting  double,  which  with  larger  tele- 
scopes than  any  of  ours  appears  as  a  triple.  The  two 
stars  that  we  see  are  of  magnitudes  six  and  seven  and  a 
half,  distance  45",  p.  42°,  colors  yellow  and  blue.  The 
third  star,  perhaps  of  thirteenth  magnitude,  is  distant 
36",  p.  245°. 

Retaining  map  No.  13  as  our  guide,  we  examine  the 
western  part  of  the  constellation  Capricornus.  Its  leader 
a  is  a  naked-eye  double,  the  two  stars  being  a  little  more 


IN  SUMMER  STAR-LANDS  85 

than  6'  apart.  Their  magnitudes  are  three  and  four,  and 
both  have  a  yellowish  hue.  The  western  star  is  a1,  and  is 
the  fainter  of  the  two.  The  other  is  designated  as  a\ 
Both  are  double.  The  components  of  a1  are  of  magni- 
tudes four  and  eight  and  a  half,  distance  44",  p.  220°. 
With  the  Washington  twenty-six-inch  telescope  a  third 
star  of  magnitude  fourteen  has  been  found  at  a  distance 
of  40",  p.  182°.  In  a2  the  magnitudes  of  the  components 
are  three  and  ten  and  a  half,  distance  7.4",  p.  150°.  The 
smaller  star  has  a  companion  of  the  twelfth  or  thirteenth 
magnitude,  distance  1.2",  p.  240°.  This,  of  course,  is 
hopelessly  beyond  our  reach.  Yet  another  star  of  magni- 
tude nine,  distance  154",  p.  156  ,  we  may  see  easily. 

Dropping  down  to  j3,  we  find  it  to  be  a  most  beautiful 
and  easy  double,  possessing  finely  contrasted  colors,  gold 
and  blue.  The  larger  star  is  of  magnitude  three,  and  the 
smaller,  the  blue  one,  of  magnitude  six,  distance  205", 
p.  267°.  Between  them  there  is  a  very  faint  star  which 
larger  telescopes  than  ours  divide  into  two,  each  of  mag- 
nitude eleven  and  a  half;  separated  3",  p.  325°. 

Still  farther  south  and  nearly  in  a  line  drawn  from  a 
through  0  we  find  a  remarkable  group  of  double  stars,  o-, 
TT,  p,  and  o.  The  last  three  form  a  beautiful  little  tri- 
angle. We  begin  with  cr,  the  faintest  of  the  four.  The 
magnitudes  of  its  components  are  six  and  nine,  distance 
54",  p.  177°.  In  TT  the  magnitudes  are  five  and  nine,  dis- 
tance 3.4",  p.  145°;  in  /o,  magnitudes  five  and  eight,  dis- 
tance 3.8",  p.  177°  (a  third  star  of  magnitude  seven  and  a 
half  is  seen  at  a  distance  of  4',  p.  150°);  in  o,  magnitudes 
six  and  seven,  distance  22",  p.  240°. 

The  star  cluster  4608  is  small,  yet,  on  a  moonless  night, 
worth  a  glance  with  the  five-inch. 

We  now  pass  northward  to  the  region  covered  by  map 
No.  14,  including  the  remainder  of  Ophiuchus  and  Serpens. 


86  PLEASURES  OF  THE  TELESCOPE 

Beginning  with  the  head  of  Serpens,  in  the  upper  right- 
hand  corner  of  the  map,  we  find  that  /:?,  of  magnitude 
three  and  a  half,  has  a  ninth-magnitude  companion,  dis- 
tance 30",  p.  265°.  The  larger  star  is  light  blue  and  the 
smaller  one  yellowish.  The  little  star  v  is  double,  mag- 
nitudes five  and  nine,  distance  50",  p.  31°,  colors  con- 
trasted but  uncertain.  In  S  we  find  a  closer  double,  mag- 
nitudes three  and  four,  distance  3.5",  p.  190°.  It  is  a 
beautiful  object  for  the  three-inch.  The  leader  of  the  con- 
stellation, a,  of  magnitude  twro  and  a  half,  has  a  faint  com- 
panion of  only  the  twelfth  magnitude,  distance  60",  p. 
350°.  The  small  star  is  bluish.  The  variable  R  has  a 
period  about  a  week  short  of  one  year,  and  at  maximum 
exceeds  the  sixth  magnitude,  although  sinking  at  mini- 
mum to  less  than  the  eleventh.  Its  color  is  ruddy. 

Passing  eastward,  we  turn  again  into  Ophiuchus,  and 
find  immediately  the  very  interesting  double,  X,  whose 
components  are  of  magnitudes  four  and  six,  distance  1", 
p.  55°.  This  is  a  long-period  binary,  and  notwithstanding 
the  closeness  of  its  stars,  our  four-inch  should  separate 
them  when  the  seeing  is  fine.  We  shall  do  better,  how- 
ever, to  try.  with  the  five-inch.  2  2166  consists  of  two 
stars  of  magnitudes  six  and  seven  and  a  half,  distance  27", 
p.  280°.  2  2173  is  a  double  of  quite  a  different  order. 
The  magnitudes  of  its  components  are  both  six,  the  dis- 
tance in  1899  0.98",  p.  331°.  It  is  evidently  a  binary  in 
rapid  motion,  as  the  distance  changed  from  about  a  quar- 
ter of  a  second  in  1881  to  more  than  a  second  in  1894.  The 
star  T  is  a  fine  triple,  magnitudes  five,  six,  and  nine,  dis- 
tances 1.8",  p.  254°,  and  100",  p.  127°.  The  close  pair  is  a 
binary  system  with  a  long  period  of  revolution,  estimated 
at  about  two  hundred  years.  We  discover  another  group 
of  remarkable  doubles  in  67,  70,  and  73.  In  the  first- 
named  star  the  magnitudes  are  four  and  eight,  distance 


88  PLEASURES  OF  THE  TELESCOPE 

55",  p.  144°,  colors  finely  contrasted,  pale  yellow  and 
red. 

Much  more  interesting,  however,  is  70,  a  binary  whose 
components  have  completed  a  revolution  since  their 
discovery  by  Sir  William  Herschel,  the  period  being 
ninety-five  years.  The  magnitudes  are  four  and  six,  or, 
according  to  Hall,  five  and  six,  distance  in  1894  2.3";  in 
1900,  1.45",  according  to  Maw.  Hall  says  the  apparent 
distance  when  the  stars  are  closest  is  about  1.7",  and  when 
they  are  widest  6.7".  This  star  is  one  of  those  whose  par- 
allax has  been  calculated  with  a  reasonable  degree  of  ac- 
curacy. Its  distance  from  us  is  about  1,260,000  times  the 
distance  of  the  sun,  the  average  distance  apart  of  the  two 
stars  is  about  2,800,000,000  miles  (equal  to  the  distance  of 
Neptune  from  the  sun),  and  their  combined  mass  is  three 
times  that  of  the  sun.  Hall  has  seen  in  the  system  of 
70  Ophiuchi  three  stars  of  the  thirteenth  magnitude  or 
less,  at  distances  of  about  60",  90",  and  165"  respectively. 

The  star  73  is  also  a  close  double,  and  beyond  our 
reach.  Its  magnitudes  are  six  and  seven,  distance  0.7", 
p.  245°.  It  is,  no  doubt,  a  binary. 

Three  star  clusters  in  Ophiuchus  remain  to  be  exam- 
ined. The  first  of  these,  No.  4256,  is  partially  resolved 
into  stars  by  the  five-inch.  No.  4315  is  globular,  and  has 
a  striking  environment  of  bystanding  stars.  It  is  about 
one  quarter  as  broad  as  the  full  moon,  and  our  largest 
aperture  reveals  the  faint  coruscation  of  its  crowded  com- 
ponents. No.  4410  is  a  coarser  and  more  scattered  star 
swarm — a  fine  sight! 

Farther  toward  the  east  we  encounter  a  part  of  Ser- 
pens  again,  which  contains  just  one  object  worth  glancing 
at,  the  double  0,  whose  stars  are  of  magnitudes  four  and 
four  and  a  half,  distance  21",  p.  104°.  Color,  both  yellow, 
the  smaller  star  having  the  deeper  hue. 


IN  SUMMER  STAR-LANDS  89 

Let  us  next,  with  the  guidance  of  map  No.  15,  enter  the 
rich  star  fields  of  Hercules,  and  of  the  head  and  first  coils 
of  Draco.  According  to  Argelander,  Hercules  contains 
more  stars  visible  to  the  naked  eye  than  any  other  con- 
stellation, and  he  makes  the  number  of  them  one  hundred 
and  fifty-five,  nearly  two  thirds  of  which  are  only  of  the 
sixth  magnitude.  But  Heis,  who  saw  more  naked-eye 
stars  than  Argelander,  makes  Ursa  Major  precisely  equal 
to  Hercules  in  the  number  of  stars,  his  enumeration  show- 
ing two  hundred  and  twenty-seven  in  each  constellation, 
while,  according  to  him,  Draco  follows  very  closely  after, 
with  two  hundred  and  twenty  stars.  Yet,  on  account  of 
the  minuteness  of  the  majority  of  their  stars,  neither  of 
these  constellations  makes  by  any  means  as  brilliant  a 
display  as  does  Orion,  to  which  Argelander  assigns  only 
one  hundred  and  fifteen  naked-eye  stars,  and  Heis  one 
hundred  and  thirty-six. 

We  begin  in  Hercules  with  the  star  K,  a  pretty  little 
double  of  magnitudes  five  and  a  half  and  seven,  distance 
31",  p.  10°,  colors  yellow  and  red.  Not  far  away  we  find, 
in  7,  a  larger  star  with  a  fainter  companion,  the  magni- 
tudes in  this  case  being  three  and  a  half  and  nine,  dis- 
tance 38",  p,  242°,  colors  white  and  faint  blue  or  lilac. 
One  of  the  most  beautiful  of  double  stars  is  a  Herculis. 
The  magnitudes  are  three  and  six,  distance  4.7",  p.  118°, 
colors  orange  and  green,  very  distinct.  Variability  has 
been  ascribed  to  each  of  the  stars  in  turn.  It  is  not 
known  that  they  constitute  a  binary  system,  because  no 
certain  evidence  of  motion  has  been  obtained.  Another 
very  beautiful  and  easily  separated  double  is  £,  magni- 
tudes three  and  eight,  distance  19",  p.  175°,  colors  pale 
green  and  purple. 

Sweeping  northwestward  to  f,  we  encounter  a  cele- 
brated binary,  to  separate  which  at  present  requires  the 

7 


90  PLEASURES  OF  THE  TELESCOPE 

higher  powers  of  a  six-inch  glass.  The  magnitudes  are 
three  and  six  and  a  half,  distance  in  1899,  0.6",  p.  264°;  in 
1900,  0.8",  p.  239°.  The  period  of  revolution  is  thirty-five 
years,  and  two  complete  revolutions  have  been  observed. 
The  apparent  distance  changes  from  0.6"  to  1.6".  They 
were  at  their  extreme  distance  in  1884. 

Two  pleasing  little  doubles  are  2  2101,  magnitudes  six 
and  nine,  distance  4",  p.  57°,  and  2  2104,  magnitudes  six 
and  eight,  distance  6",  p.  20°.  At  the  northern  end  of  the 
constellation  is  42,  a  double  that  requires  the  light-grasp- 
ing power  of  our  largest  glass.  Its  magnitudes  are  six 
and  twelve,  distance  20",  p.  94°.  In  p  we  discover  another 
distinctly  colored  double,  both  stars  being  greenish  or 
bluish,  with  a  difference  of  tone.  The  magnitudes  are 
four  and  five  and  a  half,  distance  3.7",  p.  309°.  But  «the 
double  95  is  yet  more  remarkable  for  the  colors  of  its 
stars.  Their  magnitudes  are  five  and  five  and  a  half,  dis- 
tance 6",  p.  262°,  colors,  according  to  Webb,  "  light  apple- 
green  and  cherry-red."  But  other  observers  have  noted 
different  hues,  one  calling  them  both  golden  yellow.  I 
think  Webb's  description  is  more  nearly  correct.  2  2215 
is  a  very  close  double,  requiring  larger  telescopes  than 
those  we  are  working  with.  Its  magnitudes  are  six  and  a 
half  and  eight,  distance  0.7",  p.  300°.  It  is  probably  a 
binary.  2  2289  is  also  close,  but  our  five-inch  will 
separate  it:  magnitudes  six  and  seven,  distance  1.2", 
p.  230°. 

Turning  to  ^,  we  have  to  deal  with  a  triple,  one  of 
whose  stars  is  at  present  beyond  the  reach  of  our  instru- 
ments. The  magnitudes  of  the  two  that  we  see  are  four 
and  ten,  distance  31",  p.  243°.  The  tenth-magnitude  star 
is  a  binary  of  short  period  (probably  less  than  fifty  years), 
the  distance  of  whose  components  was  2"  in  1859,  1"  in 
1880,  0.34"  in  1889,  and  0.54"  in  1891,  when  the  position 


URSA    MIN 


CORONA    BOR. 


HERCULES 


OPHIUCHUS 


MAP  No    15 


SERPENS 


92  PLEASURES  OF  THE  TELESCOPE 

angle  was  25°,  and  rapidly  increasing.  The  distance  is 
still  much  less  than  1". 

For  a  glance  at  a  planetary  nebula  we  may  turn  with 
the  five-inch  to  No.  4234.  It  is  very  small  and  faint,  only 
8"  in  diameter,  and  equal  in  brightness  to  an  eighth- 
magnitude  star.  Only  close  gazing  shows  that  it  is  not 
sharply  defined  like  a  star,  and  that  it  possesses  a  bluish 
tint.  Its  spectrum  is  gaseous. 

The  chief  attraction  of  Hercules  we  have  left  for  the 
last,  the  famous  star  cluster  between  rj  and  £,  No.  4230, 
more  commonly  known  as  M  13.  On  a  still  evening  in  the 
early  summer,  when  the  moon  is  absent  and  the  quiet  that 
the  earth  enjoys  seems  an  influence  descending  from  the 
brooding  stars,  the  spectacle  of  this  sun  cluster  in  Hercu- 
les, viewed  with  a  telescope  of  not  less  than  five-inches 
aperture,  captivates  the  mind  of  the  most  uncontempla- 
tive  observer.  With  the  Lick  telescope  I  have  watched  it 
resolve  into  separate  stars  to  its  very  center — a  scene  of 
marvelous  beauty  and  impressiveness.  But  smaller  in- 
struments reveal  only  the  in-running  star  streams  and  the 
sprinkling  of  stellar  points  over  the  main  aggregation, 
whirh  cause  it  to  sparkle  like  a  cloud  of  diamond  dust 
transfused  with  sunbeams.  The  appearance  of  flocking 
together  that  those  uncountable  thousands  of  stars  pre- 
sent calls  up  at  once  a  picture  of  our  lone  sun  separated 
from  its  nearest  stellar  neighbor  by  a  distance  probably  a 
hundred  times  as  great  as  the  entire  diameter  of  the 
spherical  space  within  which  that,  multitude  is  congre- 
gated. It  is  true  that  unless  we  assume  what  would  seem 
an  unreasonable  remoteness  for  the  Hercules  cluster,  its 
component  stars  must  be  much  smaller  bodies  than  the 
sun;  yet  even  that  fact  does  not  diminish  the  wonder  of 
their  swarming.  Here  the  imagination  must  bear  science 
on  its  wings,  else  science  can  make  no  progress  whatever. 


IX  SUMMED  STAR-LANDS  93 

It  is  an  easy  step  Jrom  Hercules  to  Draco.  In  the  con- 
spicuous diamond-shaped  figure  that  serves  as  a  guide- 
board  to  the  head  of  the  latter,  the  southernmost  star  be- 
longs not  to  Draco  but  to  Hercules.  The  brightest  star 
in  this  figure  is  7,  of  magnitude  two  and  a  half,  with 
an  eleventh-magnitude  companion,  distant  125",  p.  116°. 
Two  stars  of  magnitude  five  compose  v,  their  distance 
apart  being  62",  p.  312°.  A  more  interesting  double  is  /&, 
magnitudes  five  and  five,  distance  2.4",  p.  158°.  Both 
stars  are  white,  and  they  present  a  pretty  appearance 
when  the  air  is  steady.  They  form  a  binary  system  of 
unknown  period.  2  2078  (also  called  17  Draconis)  is  a 
triple,  magnitudes  six,  six  and  a  half,  and  six,  distances 
3.8",  p.  116°,  and  90",  p.  195°.  2  1984  is  an  easy  double, 
magnitudes  six  and  a  half  and  eight  and  a  half,  distance 
6.4",  p.  276°.  The  star  rj  is  a  very  difficult  double  for  even 
our  largest  aperture,  on  account  of  the  faintness  of  one  of 
its  components.  The  magnitudes  are  two  and  a  half  and 
ten,  distance  4.7",  p.  140°.  Its  near  neighbor,  2  2054,  may 
be  a  binary.  Its  magnitudes  are  six  and  seven,  distance 
1",  p.  0°.  In  2  2323  we  have  another  triple,  magnitudes 
five,  eight  and  a  half,  and  seven,  distances  3.6",  p.  360°, 
and  90",  p.  22°,  colors  white,  blue,  and  reddish.  A  fine 
double  is  e,  magnitudes  five  and  eight,  distance  3",  p.  5°. 

The  nebula  No.  4373  is  of  a  planetary  character,  and 
interesting  as  occupying  the  pole  of  the  ecliptic.  A  few 
years  ago  Dr.  Holden,  with  the  Lick  telescope,  discovered 
that  it  is  unique  in  its  form.  It  consists  of  a  double 
spiral,  drawn  out  nearly  in  the  line  of  sight,  like  the 
thread  of  a  screw  whose  axis  lies  approximately  endwise 
with  respect  to  the  observer.  There  is  a  central  star,  and 
another  fainter  star  is  involved  in  the  outer  spiral.  The 
form  of  this  object  suggests  strange  ideas  as  to  its  origin. 
But  the  details  mentioned  are  far  beyond  the  reach  of  our 


94  PLEASURES   OF  THE  TELESCOPE 

instruments.  We  shall  only  see  it  as  a  hazy  speck.  No. 
4415  is  another  nebula  worth  glancing  at.  It  is  Tuttle's 
so-called  variable  nebula. 

There  are  three  constellations"  represented  on  map 
No.  16  to  which  we  shall  pay  brief  visits.  First  Aquila 
demands  attention.  Its  doubles  may  be  summarized  as 
follows:  11,  magnitudes  five  and  nine,  distance  17.4",  p. 
252°;  TT,  magnitudes  six  and  seven,  distance  1.6",  p.  122°; 
23,  magnitudes  six  and  ten,  distance  3.4",  p.  12° — requires 
the  five-inch  and  good  seeing;  57,  magnitudes  five  and  six, 
distance  36",  p.  170°;  S  2654,  magnitudes  six  and  eight, 
distance  12",  p.  234°;  2  2644,  magnitudes  six  and  seven, 
distance  3.6",  p.  208°. 

The  star  rj  is  an  interesting  variable  between  magni- 
tudes three  and  a  half  and  4.7;  period,  seven  days,  four 
hours,  fourteen  minutes.  The  small  red  variable  R 
changes  from  magnitude  six  to  magnitude  seven  and  a 
half  and  back  again  in  a  period  of  three  hundred  and  fifty- 
one  days. 

Star  cluster  No.  4440  is  a  striking  object,  its  stars 
ranging  from  the  ninth  down  to  the  twelfth  magnitude. 

Just  north  of  Aquila  is  the  little  constellation  Sagitta, 
containing  several  interesting  doubles  and  many  fine  star 
fields,  which  may  be  discovered  by  sweeping  over  it  with  a 
low-power  eyepiece.  The  star  f  is  double,  magnitudes 
five  and  nine,  distance  8.6",  p.  312°.  The  larger  star  is 
itself  double,  but  far  too  close  to  be  split,  except  with  very 
large  telescopes.  In  6  we  find  three  components  of  mag- 
nitudes seven,  nine,  and  eight  respectively,  distances  11.4", 
p.  327°,  and  70",  p.  227°.  A  wide  double  is  e  magnitudes 
six  and  eight,  distance  92",  p.  81°.  Nebula  No.  4572  is 
planetary. 

Turning  to  Delphinus,  we  find  a  very  beautiful  double 
in  7,  magnitudes  four  and  five,  distance  11",  p.  273°,  colors 


VULPECULA 


HERCULES 


DELPHINUS 


AQUARIUS 


AQUILA 


CAPRICORNUS 


SAGITTARIUS 


MAP  No.  16. 


96  PLEASURES   OF  THE  TELESCOPE 

golden  and  emerald.  The  leader  a,  which  is  not  as  bright 
as  its  neighbor  /3,  and  which  is  believed  to  be  irregularly 
variable,  is  of  magnitude  four,  and  has  a  companion  of 
nine  and  a  half  magnitude  at  the  'distance  35",  p.  278°. 
At  a  similar  distance,  35",  p.  335°,  ft  has  an  eleventh- 
magnitude  companion,  and  the  main  star  is  also  double, 
but  excessively  close,  and  much  beyond  our  reach.  It 
is  believed  to  be  a  swiftly  moving  binary,  whose  stars  are 
never  separated  widely  enough  to  be  distinguished  with 
common  telescopes. 


CHAPTER    VI 

FROM    LYRA   TO    ERIDANUS 

"  This  Orpheus  struck  when  with  his  wdndrous  song 
He  charmed  the  woods  and  drew  the  rocks  along. " — MANTLIUS. 

WE  resume  our  celestial  explorations  with  the  little 
constellation  Lyra,  whose  chief  star,  Vega  (a),  has  a  very 
good  claim  to  be  regarded  as  the  most  beautiful  in  the 
sky.  The  position  of  this  remarkable  star  is  indicated  in 
map  No.  17.  Every  eye  not  insensitive  to  delicate  shades 
of  color  perceives  at  once  that  Vega  is  not  white,  but  blue- 
white.  When  the  telescope  is  turned  upon  the  star  the 
color  brightens  splendidly.  Indeed,  some  glasses  decid- 
edly exaggerate  the  blueness  of  Vega,  but  the  effect  is  so 
beautiful  that  one  can  easily  forgive  the  optical  imperfec- 
tion which  produces  it.  With  our  four-inch  we  look  for 
the  well-known  companion  of  Vega,  a  tenth-magnitude 
star,  also  of  a  blue  color  deeper  than  the  hue  of  its  great 
neighbor.  The  distance  is  50",  p.  158°.  Under  the  most 
favorable  circumstances  it  might  be  glimpsed  with  the 
three-inch,  but,  upon  the  whole,  I  should  regard  it  as  too 
severe  a  test  for  so  small  an  aperture. 

Vega  is  one  of  those  stars  which  evidently  are  not  only 
enormously  larger  than  the  sun  (one  estimate  makes  the 
ratio  in  this  case  nine  hundred  to  one),  but  whose  physical 
condition,  as  far  as  the  spectroscope  reveals  it,  is  very  dif- 
ferent from  that  of  our  ruling  orb.  Like  Sirius,  Vega  dis- 
plays the  lines  of  hydrogen  most  conspicuously,  and  it  is 

97 


98  PLEASURES  OF  THE  TELESCOPE 

probably  a  much  hotter  as  well  as  a  much  more  volumi- 
nous body  than  the  sun. 

Close  by,  toward  the  east,  two  fourth-magnitude  stars 
form  a  little  triangle  with  Vega,  f  Both  are  interesting 
objects  for  the  telescope,  and  the  northern  one,  e,  has  few 
rivals  in  this  respect.  Let  us  first  look  at  it  with  an  opera 
glass.  The  slight  magnifying  power  of  such  an  instru- 
ment divides  the  star  into  two  twinkling  points.  They 
are  about  two  and  a  quarter  minutes  of  arc  apart,  and 
exceptionally  sharp-sighted  persons  are  able  to  see  them 
divided  with  the  naked  eye.  Now  take  the  three-inch  tele- 
scope and  look  at  them,  with  a  moderate  power.  Each  of 
the  two  stars  revealed  by  the  opera  glass  appears  double, 
and  a  fifth  star  of  the  ninth  magnitude  is  seen  on  one  side 
of  an  imaginary  line  joining  the  two  pairs.  The  northern- 
most pair  is  named  e1?  the  magnitudes  being  fifth  and 
sixth,  distance  3",  p.  15°.  The  other  pair  is  e2,  magnitudes 
fifth  and  sixth,  distance  2.3",  p.  133°.  Each  pair  is  appar- 
ently a  binary;  but  the  period  of  revolution  is  unknown. 
Some  have  guessed  a  thousand  years  for  one  pair,  and  two 
thousand  for  the  other.  Another  guess  gives  el  a  period 
of  one  thousand  years,  and  e2  a  period  of  eight  hundred 
years.  Hall,  in  his  double-star  observations,  simply  says 
of  each,  "  A  slow  motion." 

Purely  by  guesswork  a  period  has  also  been  assigned 
to  the  two  pairs  in  a  supposed  revolution  around  their 
common  center,  the  time  named  being  about  a  million 
years.  It  is  not  known,  however,  that  such  a  motion  ex- 
ists. Manifestly  it  could  not  be  ascertained  within  the 
brief  period  during  which  scientific  observations  of  these 
stars  have  been  made.  The  importance  of  the  element  of 
time  in  the  study  of  stellar  motions  is  frequently  over- 
looked, though  not,  of  course,  by  those  who  are  engaged 
in  such  work.  The  sun,  for  instance,  and  many  of  the 


100  PLEASURES  OF  THE  TELESCOPE 

stars  are  known  to  be  moving  in  what  appear  to  be 
straight  lines  in  space,  but  observations  extending  over 
thousands  of  years  would  probably  show  that  these 
motions  are  in  curved  paths,  and  perhaps  in  closed 
orbits. 

If  now  in  turn  we  take  our  four-inch  glass,  we  shall  see 
something  else  in  this  strange  family  group  of  e  LyraB. 
Between  €1  and  e2,  and  placed  one  on  each  side  of  the  join- 
ing line,  appear  two  exceedingly  faint  specks  of  light, 
which  Sir  John  Herschel  made  famous  under  the  name  of 
the  debillissima.  They  are  of  the  twelfth  or  thirteenth 
magnitude,  and  possibly  variable  to  a  slight  degree.  If 
you  can  not  see  them  at  first,  turn  your  eye  toward  one 
side  of  the  field  of  view,  and  thus,  by  bringing  their  images 
upon  a  more  sensitive  part  of  the  retina,  you  may  glimpse 
them.  The  sight  is  not  much,  yet  it  will  repay  you,  as 
every  glance  into  the  depths  of  the  universe  does. 

The  other  fourth-magnitude  star  near  Vega  is  f,  a  wide 
double,  magnitudes  fourth  and  sixth,  distance  44",  p. 
150°.  Below  we  find  /3,  another  very  interesting  star, 
since  it  is  both  a  multiple  and  an  eccentric  variable.  It 
has  four  companions,  three  of  which  we  can  easily  see 
with  our  three-inch;  the  fourth  calls  for  the  five-inch;  the 
magnitudes  are  respectively  four,  seven  or  under,  eight, 
eight  and  a  half,  and  eleven;  distances  45",  p.  150°;  65", 
p.  320°;  85",  p.  20°;  and  46",  p.  248°.  The  primary,  0, 
varies  from  about  magnitude  three  and  a  half  to  magni- 
tude four  and  a  half,  the  period  being  twelve  days,  twenty- 
one  hours,  forty-six  minutes,  and  fifty-eight  seconds.  Two 
unequal  maxima  and  minima  occur  within  this  period.  In 
the  spectrum  of  this  star  some  of  the  hydrogen  lines  and 
the  D3  line  (the  latter  representing  helium,  a  constituent 
of  the  sun  and  of  some  of  the  stars,  which,  until  its  recent 
discovery  in  a  few  rare  minerals  was  not  known  to  exist 


FROM  LYRA    TO  ERIDANUS  101 

on  the  earth)  are  bright,  but  they  vary  in  visibility.  More- 
over, dark  lines  due  to  hydrogen  also  appear  in  its  spec- 
trum simultaneously  with  the  bright  lines  of  that  ele- 
ment. Then,  too,  the  bright  lines  are  sometimes  seen 
double.  Professor  Pickering's  explanation  is  that  @  Lyra3 
probably  consists  of  two  stars,  which,  like  the  two  com- 
posing /?  Auriga3,  are  too  close  to  be  separated  with  any 
telescope  now  existing,  and  that  the  body  which  gives  the 
bright  lines  is  revolving  in  a  circle  in  a  period  of  about 
twelve  days  and  twenty-two  hours  around  the  body  which 
gives  the  dark  lines.  He  has  also  suggested  that  the  ap- 
pearances could  be  accounted  for  by  supposing  a  body 
like  our  sun  to  be  rotating  in  twelve  days  and  twenty-two 
hours,  and  having  attached  to  it  an  enormous  protuber- 
ance extending  over  more  than  one  hundred  and  eighty 
degrees  of  longitude,  so  that  when  one  end  of  it  was 
approaching  us  with  the  rotation  of  the  star  the  other 
end  would  be  receding,  and  a  splitting  of  the  spectral 
lines  at  certain  periods  would  be  the  consequence.  "  The 
variation  in  light,"  he  adds,  "  may  be  caused  by  the  visi- 
bility of  a  larger  or  smaller  portion  of  this  protuber- 
ance." 

Unfortunate  star,  doomed  to  carry  its  parasitical  bur- 
den of  hydrogen  and  helium,  like  Sindbad  in  the  clasp 
of  the  Old  Man  of  the  Sea!  Surely,  the  human  imagina- 
tion is  never  so  wonderful  as  when  it  bears  an  astronomer 
on  its  wings.  Yet  it  must  be  admitted  that  the  facts  in 
this  case  are  well  calculated  to  summon  the  genius  of 
hypothesis.  And  the  puzzle  is  hardly  simplified  by  Belo- 
polsky's  observation  that  the  body  in  &  Lyra?  giving  dark 
hydrogen  lines  shows  those  lines  also  split  at  certain 
times.  It  has  been  calculated,  from  a  study  of  the  phe- 
nomena noted  above,  that  the  bright-line  star  in  0  Lyrse  is 
situated  at  a  distance  of  about  fifteen  million  miles  from 


102  PLEASURES  OF  THE  TELESCOPE 

the  center  of  gravity  of  the  curiously  complicated  system 
of  which  it  forms  a  part. 

We  have  not  yet  exhausted  the  wonders  of  Lyra.  On 
a  line  from  /3  to  7,  and  about  one"  third  of  the  distance 
from  the  former  to  the  latter,  is  the  celebrated  King 
Nebula,  indicated  on  the  map  by  the  number  4447.  We 
need  all  the  light  we  can  get  to  see  this  object  well,  and 
so,  although  the  three-inch  will  show  it,  we  shall  use  the 
five-inch.  Beginning  with  a  power  of  one  hundred  diame- 
ters, which  exhibits  it  as  a  minute  elliptical  ring,  rather 
misty,  very  soft  and  delicate,  and  yet  distinct,  we  in- 
crease the  magnification  first  to  two  hundred  and  finally 
to  three  hundred,  in  order  to  distinguish  a  little  better 
some  of  the  details  of  its  shape.  Upon  the  whole,  how- 
ever, we  find  that  the  lowest  power  that  clearly  brings 
out  the  ring  gives  the  most  satisfactory  view.  The 
circumference  of  the  ring  is  greater  than  that  of  the 
planet  Jupiter.  Its  ellipticity  is  conspicuous,  the  length 
of  the  longer  axis  being  78"  and  that  of  the  shorter  60". 
Closely  following  the  nebula  as  it  moves  through  the  field 
of  view,  our  five-inch  telescope  reveals  a  faint  star  of  the 
eleventh  or  twelfth  magnitude,  which  is  suspected  of  vari- 
ability. The  largest  instruments,  like  the  Washington 
and  the  Lick  glasses,  have  shown  perhaps  a  dozen  other 
stars  apparently  connected  with  the, nebula.  A  beautiful 
sparkling  effect  which  the  nebula  presents  was  once 
thought  to  be  an  indication  that  it  was  really  composed 
of  a  circle  of  stars,  but  the  spectroscope  shows  that  its 
constitution  is  gaseous.  Just  in  the  middle  of  the  open 
ring  is  a  feeble  star,  a  mere  spark  in  the  most  powerful 
telescope.  But  when  the  King  Nebula  is  photographed— 
and  this  is  seen  beautifully  in  the  photographs  made  with 
the  Crossley  reflector  on  Mount  Hamilton  by  the  late  Prof. 
J.  E.  Keeler — this  excessively  faint  star  imprints  its  im- 


FROM  LYRA    TO  ERIDANUS  103 

age  boldly  as  a  large  bright  blur,  encircled  by  the  nebu- 
lous ring,  which  itself  appears  to  consist  of  a  series  of 
intertwisted  spirals. 

Not  far  away  we  find  a  difficult  double  star,  17,  whose 
components  are  of  magnitudes  six  and  ten  or  eleven,  dis- 
tance 3.7",  p.  325°. 

From  Lyra  we  pass  to  Cygnus,  which,  lying  in  one  of 
the  richest  parts  of  the  Milky  Way,  is  a  very  interesting 
constellation  for  the  possessor  of  a  telescope.  Its  general 
outlines  are  plainly  marked  for  the  naked  eye  by  the 
figure  of  a  cross  more  than  twenty  degrees  in  length  lying 
along  the  axis  of  the  Milky  Way.  The  foot  of  the  cross  is 
indicated  by  the  star  £,  also  known  as  Albireo,  one  of  the 
most  charming  of  all  the  double  stars.  The  three-inch 
amply  suffices  to  reveal  the  beauty  of  this  object,  whose 
components  present  as  sharp  a  contrast  of  light  yellow 
and  deep  blue  as  it  would  be  possible  to  produce  artificially 
with  the  purest  pigments.  The  magnitudes  are  three  and 
seven,  distance  34.6",  p.  55°.  No  motion  has  been  de- 
tected indicating  that  these  stars  are  connected  in  orbital 
revolution,  yet  no  one  can  look  at  them  without  feeling 
that  they  are  intimately  related  to  one  another.  It  is  a 
sight  to  which  one  returns  again  and  again,  always  with 
undiminished  pleasure.  The  most  inexperienced  observer 
admires  its  beauty,  and  after  an  hour  spent  with  doubtful 
results  in  trying  to  interest  a  tyro  in  double  stars  it  is 
always  with  a  sense  of  assured  success  that  one  turns  the 
telescope  to  fi  Cygni. 

Following  up  the  beam  of  the  imaginary  cross  along 
the  current  of  the  Milky  Way,  every  square  degree  of 
which  is  here  worth  long  gazing  into,  we  come  to  a  pair 
of  stars  which  contend  for  the  name-letter  x-  On  our 
map  the  letter  is  attached  to  the  southernmost  of  the  two, 
a  variable  of  long  period — four  hundred  and  six  days — 


104  PLEASURES  OF  THE  TELESCOPE 

whose  changes  of  brilliance  lie  between  magnitudes  four 
and  thirteen,  but  which  exhibits  much  irregularity  in  its 
maxima.  The  other  star,  not  named  but  easily  recognized 
in  the  map,  is  sometimes  called  IT.  It  is  an  attractive 
double  whose  colors  faintly  reproduce  those  of  ft.  The 
magnitudes  are  five  and  eight,  distance  26",  p.  73°. 
Where  the  two  arms  of  the  cross  meet  is  y,  whose  remark- 
able cortege  of  small  stars  running  in  curved  streams 
should  not  be  missed.  Use  the  lowest  magnifying  power. 

At  the  extremity  of  the  western  arm  of  the  cross  is  S, 
a  close  double,  difficult  for  telescopes  of  moderate  aper- 
ture on  account  of  the  difference  in  the  magnitudes  of  the 
components.  We  may  succeed  in  dividing  it  with  the  five- 
inch.  The  magnitudes  are  three  and  eight,  distance  1.5", 
p.  310°.  It  is  regarded  as  a  binary  of  long  and  as  yet 
unascertained  period. 

In  o2  we  find  a  star  of  magnitude  four  and  orange  in 
color,  having  two  blue  companions,  the  first  of  magnitude 
seven  and  a  half,  distance  107",  p.  174°,  and  the  second 
of  magnitude  five  and  a  half,  distance  358",  p.  324°.  Far- 
ther north  is  ^,  which  presents  to  us  the  combination  of 
a  white  five-and-a-half-magnitude  star  with  a  lilac  star  of 
magnitude  seven  and  a  half.  The  distance  is  3",  p.  184°. 
A  very  pretty  sight. 

We  now  pass  to  the  extremity  of  the  other  arm  of  the 
cross,  near  which  lies  the  beautiful  little  double  49,  whose 
components  are  of  magnitudes  six  and  eight,  distance  2.8", 
p.  50°.  The  colors  are  yellow  and  blue,  conspicuous  and 
finely  contrasted.  A  neighboring  double  of  similar  hues 
is  52,  in  which  the  magnitudes  are  four  and  nine,  distance 
6",  p.  60°.  Sweeping  a  little  way  northward  we  come 
upon  an  interesting  binary,  \,  which  is  unfortunately  be- 
yond the  dividing  power  of  our  largest  glass.  A  good 
seven-inch  or  seven-and-a-half-inch  should  split  it  under 


FROM  LYRA    TO  ERIDANU8  105 

favorable  circumstances.  Its  magnitudes  are  six  and 
seven,  distance  0.66",  p.  74°. 

The  next  step  carries  us  to  a  very  famous  object,  61 
Cygni,  long  known  as  the  nearest  star  in  the  northern 
hemisphere  of  the  heavens.  It  is  a  double  which  our 
three-inch  will  readily  divide,  the  magnitudes  being  both 
six,  distance  21",  p.  122°.  The  distance  of  61  Cygni,  accord- 
ing to  Hall's  parallax  of  0.27",  is  about  70,000,000,000,000 
miles.  There  is  some  question  whether  or  not  it  is  a 
binary,  for,  while  the  twin  stars  are  both  moving  in  the 
same  direction  in  space  with  comparative  rapidity,  yet 
conclusive  evidence  of  orbital  motion  is  lacking.  When 
one  has  noticed  the  contrast  in  apparent  size  between  this 
comparatively  near-by  star,  which  the  naked  eye  only 
detects  with  considerable  difficulty,  and  some  of  its  bril- 
liant neighbors  whose  distance  is  so  great  as  to  be  im- 
measurable with  our  present  means,  no  better  proof  will 
be  needed  of  the  fact  that  the  faintness  of  a  star  is  not 
necessarily  an  indication  of  remoteness. 

We  may  prepare  our  eyes  for  a  beautiful  exhibition  of 
contrasted  colors  once  more  in  the  star  /*.  This  is  really 
a  quadruple,  although  only  two  of  its  components  are 
close  and  conspicuous.  The  magnitudes  are  five,  six, 
seven  and  a  half,  and  twelve;  distances  2.4",  p,  121°;  208", 
p.  56°;  and  35",  p.  264°.  The  color  of  the  largest  star  is 
white  and  that  of  its  nearest  companion  blue;  the  star  of 
magnitude  seven  and  a  half  is  also  blue. 

The  star  cluster  4681  is  a  fine  sight  with  our  largest 
glass.  In  the  map  we  find  the  place  marked  where  the 
new  star  of  1876  made  its  appearance.  This  was  first 
noticed  on  November  24,  1876,  when  it  shone  with  the 
brilliance  of  a  star  of  magnitude  three  and  a  half.  Its 
spectrum  was  carefully  studied,  especially  by  Vogel,  and 
the  very  interesting  changes  that  it  underwent  were 

8 


106  PLEASURES  OF  THE  TELESCOPE 

noted.  Within  a  year  the  star  had  faded  to  less  than 
the  tenth  magnitude,  and  its  spectrum  had  completely 
changed  in  appearance,  and  had  come  to  bear  a  close  re- 
semblance to  that  of  a  planetary  nebula.  This  has  been 
quoted  as  a  possible  instance  of  a  celestial  collision 
through  whose  effects  the  solid  colliding  masses  were 
vaporized  and  expanded  into  a  nebula.  At  present  the 
star  is  very  faint  and  can  only  be  seen  with  the  most 
powerful  telescopes.  Compare  with  the  case  of  Nova 
Auriga?,  previously  discussed. 

Underneath  Cygnus  we  notice  the  small  constellation 
Vulpecula.  It  contains  a  few  objects  worthy  of  attention, 
the  first  being  the  nebula  4532,  the  "  dumb-bell  nebula  " 
of  Lord  Eosse.  With  the  four-inch,  and  better  with  the 
five-inch,  we  are  able  to  perceive  that  it  consists  of  two 
close-lying  tufts  of  misty  light.  Many  stars  surround  it, 
and  large  telescopes  show  them  scattered  between  the 
two  main  masses  of  the  nebula.  The  Lick  photographs 
show  that  its  structure  is  spiral.  The  star  11  points  out 
the  place  where  a  new  star  of  the  third  magnitude  ap- 
peared in  1670.  2  2695  is  a  close  double,  magnitudes  six 
and  eight,  distance  0.96",  p.  78°. 

We  turn  to  map  No.  18,  and,  beginning  at  the  western 
end  of  the  constellation  Aquarius,  we  find  the  variable  T, 
which  ranges  between  magnitudes  seven  and  thirteen  in 
a  period  of  about  two  hundred  and  three  days.  Its  near 
neighbor  2  2729  is  a  very  close  double,  beyond  the  sepa- 
rating power  of  our  five-inch,  the  magnitudes  being  six 
and  seven,  distance  0.6",  p.  176°.  2  2745,  also  known  as 
12  Aquarii,  is  a  good  double  for  the  three-inch.  Its  mag- 
nitudes are  six  and  eight,  distance  2.8",  p.  190°.  In  £  we 
discover  a  beauty.  It  is  a  slow  binary  of  magnitudes  four 
and  four,  distance  3.1",  p.  321°.  According  to  some  ob- 
servers both  stars  have  a  greenish  tinge.  The  star  41  is  a 


108  PLEASURES  OF  THE  TELESCOPE 

wider  double,  magnitudes  six  and  eight,  distance  5",  p. 
115°,  colors  yellow  and  blue.  The  uncommon  stellar  con- 
trast of  white  with  light  garnet  is  exhibited  by  T,  mag- 
nitudes six  and  nine,  distance  27",  p.  115°.  Yellow  and 
blue  occur  again  conspicuously  in  ^,  magnitudes  four  and 
a  half  and  eight  and  a  half,  distance  50",  p.  310°.  Kose 
and  emerald  have  been  recorded  as  the  colors  exhibited 
in  2  2998,  whose  magnitudes  are  five  and  seven,  distance 
1.3",  p.  346°. 

The  variables  S  and  R  are  both  red.  The  former 
ranges  between  magnitudes  eight  and  twelve,  period  two 
hundred  and  eighty  days,  and  the  latter  between  magni- 
tudes six  and  eleven,  period  about  three  hundred  and 
ninety  days. 

The  nebula  4628  is  Kosse's  "  Saturn  nebula,"  so  called 
because  with  his  great  telescope  it  presented  the  appear- 
ance of  a  nebulous  model  of  the  planet  Saturn.  With  our 
five-inch  we  see  it  simply  as  a  planetary  nebula.  We  may 
also  glance  at  another  nebula,  4678,  which  appears  circu- 
lar and  is  pinned  with  a  little  star  at  the  edge. 

The  small  constellation  Equuleus  contains  a  surpris- 
ingly large  number  of  interesting  objects.  2  2735  is  a 
rather  close  double,  magnitudes  six  and  eight,  distance 
1.8",  p.  287°.  2  2737  (the  first  star  to  the  left  of  2  2735, 
the  name  having  accidentally  been  omitted  from  the  map) 
is  a  beautiful  triple,  although  the  two  closest  stars,  of 
magnitudes  six  and  seven,  can  not  be  separated  by  our 
instruments.  Their  distance  in  1886  was  0.78",  p.  286°, 
and  they  had  then  been  closing  rapidly  since  1884,  when  the 
distance  was  1.26".  The  third  star,  of  magnitude  eight,  is 
distant  11",  p.  75°.  2  2744  consists  of  two  stars,  mag- 
nitudes six  and  seven,  distance  1.4",  p.  1.67°.  It  is  prob- 
ably a  binary,  2  2742  is  a  wider  double,  magnitudes  both 
six,  distance  2.6",  p.  225°.  Another  triple,  one  of  whose 


FROM  LYRA    TO  ERIDANUS  109 

components  is  beyond  our  reach,  is  7.  Here  the  mag- 
nitudes are  fifth,  twelfth,  and  sixth,  distances  2",  p.  274° 
and  366".  It  would  also  be  useless  for  us  to  try  to  sepa- 
rate S,  but  it  is  interesting  to  remember  that  this  is  one 
of  the  closest  of  known  double  stars,  the  magnitudes 
being  fourth  and  fifth,  distance  0.4",  p.  198°.  These  data 
are  from  HalPs  measurements  in  1887.  The  star  is,  no 
doubt,  a  binary.  With  the  five-inch  we  may  detect  one 
and  perhaps  two  of  the  companion  stars  in  the  quadruple 
/3.  The  magnitudes  are  five,  ten,  and  two  eleven,  dis- 
tances 67",  p.  309°;  86",  p.  276°;  and  6.5",  p.  15°.  The 
close  pair  is  comprised  in  the  tenth-magnitude  star. 

Map  No.  19  introduces  us  to  the  constellation  Pegasus, 
which  is  comparatively  barren  to  the  naked  eye,  and  by  no 
means  rich  in  telescopic  phenomena.  The  star  e,  of  mag- 
nitude two  and  a  half,  has  a  blue  companion  of  the  eighth 
magnitude,  distance  138",  p.  324°;  colors  yellow  and 
violet.  A  curious  experiment  that  may  be  tried  with  this 
star  is  described  by  Webb,  who  ascribes  the  discovery  of 
the  phenomenon  to  Sir  John  Herschel.  When  near  the 
meridian  the  small  star  in  e  appears,  in  the  telescope, 
underneath  the  large  one.  If  now  the  tube  of  the  tele- 
scope be  slightly  swung  from  side  to  side  the  small  star 
will  appear  to  describe  a  pendulumlike  movement  with 
respect  to  the  large  one.  The  explanation  suggested  is 
that  the  comparative  faintness  of  the  small  star  causes 
its  light  to  affect  the  retina  of  the  eye  less  quickly  than 
does  that  of  its  brighter  companion,  and,  in  consequence, 
the  reversal  of  its  apparent  motion  with  the  swinging  of 
the  telescope  is  not  perceived  so  soon. 

The  third-magnitude  star  ^  has  a  companion  of  mag- 
nitude ten  and  a  half,  distance  90",  p.  340°.  The  star  /?, 
of  the  second  magnitude,  and  reddish,  is  variable  to  the 
extent  of  half  a  magnitude  in  an  irregular  period,  and  7. 


FROM  LYRA    TO  ERIDANU8  HI 

of  magnitude  two  and  a  half,  has  an  eleventh-magnitude 
companion,  distance  162",  p.  285°. 

Our  interest  is  revived  on  turning,  with  the  guidance 
of  map  No.  20,  from  the  comparative  poverty  of  Pegasus 
to  the  spacious  constellation  Cetus.  The  first  double  star 
that  we  meet  in  this  constellation  is  26,  whose  compo- 
nents are  of  magnitudes  six  and  nine,  distance  16.4", 
p.  252°;  colors,  topaz  and  lilac.  Not  far  away  is  the 
closer  double  42,  composed  of  a  sixth  and  a  seventh  mag- 
nitude star,  distance  1.25",  p.  350°.  The  four-inch  is 
capable  of  splitting  this  star,  but  we  shall  do  better  to 
use  the  five-inch.  In  passing  we  may  glance  at  the  tenth- 
magnitude  companion  to  97,  distance  225",  p.  304°.  An- 
other wide  pair  is  found  in  ?,  magnitudes  three  and  nine, 
distance  185",  p.  40°. 

The  next  step  brings  us  to  the  wonderful  variable  o, 
or  Mira,  whose  changes  have  been  watched  for  three 
centuries,  the  first  observer  of  the  variability  of  the  star 
having  been  David  Fabricius  in  1596.  Not  only  is  the 
range  of  variability  very  great,  but  the  period  is  remark- 
ably irregular.  In  the  time  of  Hevelius,  Mira  was  once 
invisible  for  four  years.  When  brightest,  the  star  is  of 
about  the  second  magnitude,  and  when  faintest,  of  the 
ninth  magnitude,  but  at  maximum  it  seldom  exhibits  the 
greatest  brilliance  that  it  has  on  a  few  occasions  shown 
itself  capable  of  attaining.  Ordinarily  it  begins  to  fade 
after  reaching  the  fourth  or  fifth  magnitude.  The  period 
averages  about  three  hundred  and  thirty-one  days,  but  is 
irregularly  variable  to  the  extent  of  twenty-five  days.  Its 
color  is  red,  and  its  spectrum  shows  bright  lines,  which  it 
is  believed  disappear  when  the  star  sinks  to  a  minimum. 
Among  the  various  theories  proposed  to  account  for  such 
changes  as  these  the  most  probable  appears  to  be  that 
which  ascribes  them  to  some  cause  analogous  to  that 


FROM  LYEA    TO  ERIDANUS  113 

operating  in  the  production  of  sun  spots.  The  outburst 
of  light,  however,  as  pointed  out  by  Schemer,  should  be 
regarded  as  corresponding  to  the  maximum  and  not  the 
minimum  stage  of  sun-spot  activity.  According  to  this 
view,  the  star  is  to  be  regarded  as  possessing  an  extensive 
atmosphere  of  hydrogen,  which,  during  the  maximum,  is 
upheaved  into  enormous  prominences,  and  the  brilliance 
of  the  light  from  these  prominences  suffices  to  swamp  the 
photospheric  light,  so  that  in  the  spectrum  the  hydrogen 
lines  appear  bright  instead  of  dark. 

It  is  not  possible  to  suppose  that  Mira  can  be  the 
center  of  a  system  of  habitable  planets,  no  matter  what 
we  may  think  of  the  more  constant  stars  in  that  regard, 
because  its  radiation  manifestly  increases  more  than  six 
hundred  fold,  and  then  falls  off  again  to  an  equal  extent 
once  in  every  ten  or  eleven  months.  I  have  met  people 
who  can  not  believe  that  the  Almighty  would  make  a  sun 
and  then  allow  its  energies  "  to  go  to  waste,"  by  not  sup- 
plying it  with  a  family  of  worlds.  But  I  imagine  that  if 
they  had  to  live  within  the  precincts  of  Mira  Ceti  they 
would  cry  out  for  exemption  from  their  own  law  of  stellar 
utility. 

The  most  beautiful  double  star  in  Cetus  is  y,  magni- 
tudes three  and  seven,  distance  3",  p.  288°;  hues,  straw- 
color  and  blue.  The  leading  star  a,  of  magnitude  two  and 
a  half,  has  a  distant  blue  companion  three  magnitudes 
fainter,  and  between  them  are  two  minute  stars,  the 
southernmost  of  which  is  a  double,  magnitudes  both 
eleven,  distance  10",  p.  225°. 

The  variable  S  ranges  between  magnitudes  seven  and 
twelve  in  a  somewhat  irregular  period  of  about  eleven 
months,  while  K  ranges  between  the  seventh  and  the  thir- 
teenth magnitudes  in  a  period  of  one  hundred  and  sixty- 
seven  days. 


114  PLEASURES   OF  THE  TELESCOPE 

The  constellation  Eridanus,  represented  in  map  No.  21, 
contains  a  few  fine  double  stars,  one  of  the  most  interest- 
ing of  which  is  12,  a  rather  close  binary.  The  magnitudes 
are  four  and  eight,  distance  2",  p.'  327°.  We  shall  take 
the  five-inch  for  this,  and  a  steady  atmosphere  and  sharp 
seeing  will  be  necessary  on  account  of  the  wide  difference 
in  the  brightness  of  the  component  stars.  Amateurs  fre- 
quently fail  to  make  due  allowance  for  the  effect  of  such 
difference.  When  the  limit  of  separating  power  for  a 
telescope  of  a  particular  aperture  is  set  at  1"  or  2",  as  the 
case  may  be,  it  is  assumed  that  the  stars  composing  the 
doubles  on  which  the  test  is  made  shall  be  of  nearly  the 
same  magnitude,  or  at  least  that  they  shall  not  differ  by 
more  than  one  or  two  magnitudes  at  the  most.  The  stray 
light  surrounding  a  comparatively  bright  star  tends  to 
conceal  a  faint  companion,  although  the  telescope  may 
perfectly  separate  them  so  far  as  the  stellar  disks  are  con- 
cerned. Then,  too,  I  have  observed  in  my  own  experience 
that  a  very  faint  and  close  double  is  more  difficult  than  a 
brighter  pair  not  more  widely  separated,  usually  on  ac- 
count of  the  defect  of  light,  and  this  is  true  even  when 
the  components  of  the  faint  double  are  of  equal  mag- 
nitude. 

2  470,  otherwise  known  as  32  Eridani,  is  a  superb 
object  on  account  of  the  colors  of  its  components,  the 
larger  star  being  a  rich  topaz  and  the  smaller  an  ultra- 
marine; while  the  difference  in  magnitude  is  not  as  great 
as  in  many  of  the  colored  doubles.  The  magnitudes  are 
five  and  seven,  distance  6.7",  p.  348°.  The  star  y,  of  mag- 
nitude two  and  a  half,  has  a  tenth-magnitude  companion, 
distant  51",  p.  238°.  S  516,  also  called  39  Eridani,  con- 
sists of  two  stars  of  magnitudes  six  and  nine,  distance 
6.4",  p.  150°;  colors,  yellow  and  blue.  The  supposed 
binary  character  of  this  star  has  not  yet  been  established. 


116  PLEASURES  OF  THE  TELESCOPE 

In  o2  we  come  upon  an  interesting  triple  star,  two  of 
whose  components  at  any  rate  we  can  easily  see.  The 
largest  component  is  of  'the  fourth  magnitude.  At  a  dis- 
tance of  82",  p.  105°,  we  find  a  fenth-magnitude  com- 
panion. This  companion  is  itself  double,  the  magnitudes 
of  its  components  being  ten  and  eleven,  distance  2.6", 
p.  98°.  Hall  says  of  these  stars  that  they  "  form  a  re- 
markable system."  He  has  also  observed  a  fourth  star 
of  the  twelfth  magnitude,  distant  45"  from  the  largest 
star,  p.  85°.  This  is  apparently  unconnected  with  the 
others,  although  it  is  only  half  as  distant  as  the  tenth- 
magnitude  component  is  from  the  primary.  2  590  is  in- 
teresting because  of  the  similarity  of  its  two  components 
in  size,  both  being  of  about  the  seventh  magnitude,  dis- 
tance 10",  p.  318°. 

Finally,  we  turn  to  the  nebula  826.  This  is  planetary 
in  form  and  inconspicuous,  but  Lassell  has  described  it  as 
presenting  a  most  extraordinary  appearance  with  his 
great  reflector — a  circular  nebula  lying  upon  another 
fainter  and  larger  nebula  of  a  similar  shape,  and  having  a 
star  in  its  center.  Yet  it  may  possibly  be  an  immensely 
distant  star  cluster  instead  of  a  nebula,  since  its  spectrum 
does  not  appear  to  be  gaseous. 


CHAPTER    VII 

PISCES,    ARIES,   TAURUS,    AND   THE    NORTHERN    STARS 

' '  Now  sing  we  stormy  skies  when  Autumn  weighs 
The  year,  and  adds  to  nights  and  shortens  days, 
And  suns  declining  shine  with  feeble  rays." — DRYDEN'S  VIRGIL. 

THE  eastern  end  of  Pisces,  represented  in  map  No.  22, 
includes  most  of  the  interesting  telescopic  objects  that 
the  constellation  contains.  We  begin  our  exploration  at 
the  star  numbered  55,  a  double  that  is  very  beautiful  when 
viewed  with  the  three-inch  glass.  The  components  are  of 
magnitudes  five  and  eight,  distance  6.6",  p.  192°.  The  larger 
star  is  yellow  and  the  smaller  deep  blue.  The  star  65,  while 
lacking  the  peculiar  charm  of  contrasted  colors  so  finely 
displayed  in  55,  possesses  an  attraction  in  the  equality  of 
its  components  which  are  both  of  the  sixth  magnitude  and 
milk-white.  The  distance  is  4.5",  p.  118°.  In  66  we  find  a 
swift  binary  whose  components  are  at  present  far  too 
close  for  any  except  the  largest  telescopes.  The  distance 
in  1894  was  only  0.36",  p.  329°.  The  magnitudes  are  six 
and  seven.  In  contrast  with  this  excessively  close  double 
is  -fr,  whose  components  are  both  of  magnitude  five  and  a 
half,  distance  30",  p.  160°.  Dropping  down  to  77  we  come 
upon  another  very  wide  and  pleasing  double,  magnitudes 
six  and  seven,  distance  33",  p.  82°,  colors  white  and  lilac 
or  pale  blue.  Hardly  less  beautiful  is  f,  magnitudes  five 
and  six,  distance  24",  p.  64°.  Finest  of  all  is  a,  which  ex- 
hibits a  remarkable  color  contrast,  the  larger  star  being 

117 


118  PLEASURES  OF  THE  TELESCOPE 

greenish  and  the  smaller  blue.  The  magnitudes  are  four 
and  five,  distance  3",  p.  320°.  This  star  is  a  binary,  but 
the  motion  is  slow.  The  variable  K  ranges  between  mag- 
nitudes seven  and  thirteen,  period  three  hundred  and 
forty-four  days. 

The  constellation  Aries  contains  several  beautiful 
doubles,  all  but  one  of  which  are  easy  for  our  smallest 
aperture.  The  most  striking  of  these  is  7,  which  is  his- 
torically interesting  as  the  first  double  star  discovered. 
The  discovery  was  made  by  Robert  Hooke  in  1664  by  acci- 
dent, while  he  was  following  the  comet  of  that  year  with 
his  telescope.  He  expressed  great  surprise  on  noticing 
that  the  glass  divided  the  star,  and  remarked  that  he  had 
not  met  with  a  like  instance  in  all  the  heavens.  His  ob- 
servations could  not  have  been  very  extensive  or  very 
carefully  conducted,  for  there  are  many  double  stars  much 
wider  than  7  Arietis  which  Hooke  could  certainly  have 
separated  if  he  had  examined  them.  The  magnitudes  of 
the  components  of  7  are  four  and  four  and  a  half,  or, 
according  to  Hall,  both  four;  distance  8.5",  p.  180°.  A 
few  degrees  above  7,  passing  by  /3,  is  a  wide  double  X, 
magnitudes  five  and  eight,  distance  37",  p.  45°,  colors 
white  and  lilac  or  violet.  Three  stars  are  to  be  seen  in 
14:  magnitudes  five  and  a  half,  ten,  and  nine,  distances 
83",  p.  36°,  and  106",  p.  278°,  colors  white,  blue,  and  lilac. 
The  star  30  is  a  very  pretty  double,  magnitudes  six  and 
seven,  distance  38.6",  p.  273°.  2  289  consists  of  a  topaz 
star  combined  with  a  sapphire,  magnitudes  six  and  nine, 
distance  28.5",  p.  0°.  The  fourth-magnitude  star  41  has 
several  faint  companions.  The  magnitudes  of  two  of 
these  are  eleven  and  nine,  distances  34",  p.  203°,  and  130", 
p.  230°.  We  discover  another  triple  in  TT,  magnitudes  five, 
eight,  and  eleven,  distances  3.24",  p.  122°,  and  25",  p.  110°. 
The  double  mentioned  above  as  being  too  close  for  our 


120  PLEASURES  OF  THE  TELESCOPE 

three-inch  glass  is  e,  which,  however,  can  be  divided  with 
the  four-inch,  although  the  five-inch  will  serve  us  better. 
The  magnitudes  are  five  and  a  half  and  six,  distance  1.26", 
p.  202°.  The  star  52  has  two  companions,  one  of  which 
is  so  close  that  our  instruments  can  not  separate  it,  while 
the  other  is  too  faint  to  be  visible  in  the  light  of  its  bril- 
liant neighbor  without  the  aid  of  a  very  powerful  tele- 
scope. 

We  are  now  about  to  enter  one  of  the  most  magnificent 
regions  in  the  sky,  which  is  hardly  less  attractive  to  the 
naked  eye  than  Orion,  and  which  men  must  have  admired 
from  the  beginning  of  their  history  on  the  earth,  the  con- 
stellation Taurus  (map  No.  23).  Two  groups  of  stars 
especially  distinguish  Taurus,  the  Hyades  and  the  Plei- 
ades, and  both  are  exceedingly  interesting  when  viewed 
with  the  lowest  magnifying  powers  of  our  telescopes. 

We  shall  begin  with  a  little  star  just  west  of  the 
Pleiades,  2  412,  also  called  7  Tauri.  This  is  a  triple,  but 
we  can  see  it  only  as  a  double,  the  third  star  being  ex- 
ceedingly close  to  the  primary.  The  magnitudes  are  six 
and  a  half,  seven,  and  ten,  distances  0.3",  p.  216°,  and  22", 
p.  62°.  In  the  Pleiades  we  naturally  turn  to  the  brightest 
star  97,  or  Alcyone,  famous  for  having  once  been  regarded 
as  the  central  sun  around  which  our  sun  and  a  multitude 
of  other  luminaries  were  supposed  to  revolve,  and  pic- 
turesque on  account  of  the  little  triangle  of  small  stars 
near  it  which  the  least  telescopic  assistance  enables  us 
to  see.  One  may  derive  much  pleasure  from  a  study  of 
the  various  groupings  of  stars  in  the  Pleiades.  Photog- 
raphy has  demonstrated,  what  had  long  been  suspected 
from  occasional  glimpses  revealed  by  the  telescope,  that 
this  celebrated  cluster  of  stars  is  intermingled  with  curi- 
ous forms  of  nebulae.  The  nebulous  matter  appears  in 
festoons,  apparently  attached  to  some  of  the  larger  stars, 


122  PLEASURES  OF  THE  TELESCOPE 

such  as  Alcyone,  Merope,  and  Maia,  and  in  long,  narrow, 
straight  lines,  the  most  remarkable  of  which,  a  faintly 
luminous  thread  starting  midway  between  Maia  and  Alcy- 
one and  running  eastward  some  40*,  is  beaded  with  seven 
or  eight  stars.  The  width  of  this  strange  nebulous  streak 
is,  on  an  average,  3"  or  4",  and  there  is,  perhaps,  no  more 
wonderful  phenomenon  anywhere  in  celestial  space.  Un- 
fortunately, no  telescope  is  able  to  show  it,  and  all  our 
knowledge  about  it  is  based  upon  photographs.  It  might 
be  supposed  that  it  was  a  nebulous  disk  seen  edgewise, 
but  for  the  fact  that  at  the  largest  star  involved  in  its 
course  it  bends  sharply  about  10°  out  of  its  former  direc- 
tion, and  for  the  additional  fact  that  it  seems  to  take  its 
origin  from  a  curved  offshoot  of  the  intricate  nebulous 
mass  surrounding  Maia.  Exactly  at  the  point  where  this 
curve  is  transformed  into  a  straight  line  shines  a  small 
star!  In  view  of  all  the  facts  the  idea  does  not  seem  to 
be  very  far-fetched  that  in  the  Pleiades  we  behold  an  as- 
semblage of  suns,  large  and  small,  formed  by  the  gradual 
condensation  of  a  nebula,  and  in  which  evolution  has  gone 
on  far  beyond  the  stage  represented  by  the  Orion  nebula, 
where  also  a  group  of  stars  may  be  in  process  of  forma- 
tion out  of  nebulous  matter.  If  we  look  a  little  farther 
along  this  line  of  development,  we  may  perceive  in  such 
a  stellar  assemblage  as  the  cluster  in  Hercules,  a  still 
later  phase  wherein  all  the  originally  scattered  material 
has,  perhaps,  been  absorbed  into  the  starry  nuclei. 

The  yellow  star  2  430  has  two  companions:  magni- 
tudes six,  nine,  and  nine  and  a  half,  distances  26",  p.  55°, 
and  39",  p.  302°.  The  star  30  of  the  fifth  magnitude  has  a 
companion  of  the  ninth  magnitude,  distance  9",  p.  58°, 
colors  emerald  and  purple,  faint.  An  interesting  vari- 
able, of  the  type  of  Algol,  is  X,  which  at  maximum  is  of 
magnitude  three  and  four  tenths  and  at  minimum  of  mag- 


PISCES,  ARIES,  TAURUS,  AND  THE  NORTHERN  STARS    123 

nitude  four  and  two  tenths.  Its  period  from  one  maxi- 
mum to  the  next  is  about  three  days  and  twenty-three 
hours,  but  the  actual  changes  occupy  only  about  ten 
hours,  and  it  loses  light  more  swiftly  than  it  regains  it. 
A  combination  of  red  and  blue  is  presented  by  <£  (mis- 
takenly marked  on  map  No.  23  as  ^).  The  magnitudes 
are  six  and  eight,  distance  56",  p.  242°.  A  double  of  simi- 
lar magnitudes  is  %,  distance  19",  p.  25°.  Between  the 
two  stars  which  the  naked  eye  sees  in  K  is  a  minute  pair, 
-each  of  less  than  the  eleventh  magnitude,  distance  5",  p. 
324°.  Another  naked-eye  double  is  formed  by  01  and  02,  in 
the  Hyades.  The  magnitudes  are  five  and  five  and  a  half, 
distance  about  5'  37". 

The  leading  star  of  Taurus,  Aldebaran  (a),  is  celebrated 
for  its  reddish  color.  The  precise  hue  is  rather  uncertain, 
but  Aldebaran  is  not  orange  as  Betelgeuse  in  Orion  is, 
and  no  correct  eye  can  for  an  instant  confuse  the  colors 
of  these  two  stars,  although  many  persons  seem  to  be  un- 
able to  detect  the  very  plain  difference  between  them  in 
this  respect.  Aldebaran  has  been  called  "  rose-red,"  and 
it  would  be  an  interesting  occupation  for  an  amateur  to 
determine,  with  the  aid  of  some  proper  color  scale,  the 
precise  hue  of  this  star,  and  of  the  many  other  stars  which 
exhibit  chromatic  idiosyncrasy.  Aldebaran  is  further  in- 
teresting as  being  a  standard  first-magnitude  star.  With 
the  four-inch  glass  we  see  without  difficulty  the  tenth- 
magnitude  companion  following  Aldebaran  at  a  distance 
of  114",  p.  35°.  There  is  an  almost  inexplicable  charm 
about  these  faint  attendants  of  bright  stars,  which  is 
quite  different  from  the  interest  attaching  to  a  close  and 
nearly  equal  pair.  The  impression  of  physical  relation- 
ship is  never  lacking  though  it  may  be  deceptive,  and  this 
awakens  a  lively  appreciation  of  the  vast  differences  of 
magnitude  that  exist  among  the  different  suns  of  space. 


124  PLEASURES  OF  THE  TELESCOPE 

The  actual  size  and  might  of  this  great  red  sun  form 
an  attractive  subject  for  contemplation.  As  it  appears  to 
our  eyes  Aldebaran  gives  one  twenty-five-thousand-mil- 
lionth as  much  light  as  the  sun,  but'  if  we  were  placed  mid- 
way between  them  the  star  would  outshine  the  sun  in  the 
ratio  of  not  less  than  160  to  1.  And  yet,  gigantic  as  it 
is,  Aldebaran  is  possibly  a  pygmy  in  comparison  with 
Arcturus,  whose  possible  dimensions  were  discussed  in 
the  chapter  relating  to  Bootes.  Although  Aldebaran  is 
known  to  possess  several  of  the  metallic  elements  that 
exist  in  the  sun,  its  spectrum  differs  widely  from  the  solar 
spectrum  in  some  respects,  and  more  closely  resembles 
that  of  Arcturus. 

Other  interesting  objects  in  Taurus  are  <r,  divisible 
with  the  naked  eye,  magnitudes  five  and  five  and  a  half, 
distance  7';  2  674,  double,  magnitudes  six  and  nine,  dis- 
tance 10.5",  p.  147°;  S  716,  double,  magnitudes  six  and 
seven,  distance  5",  p.  200° — a  pleasing  sight;  T,  triple, 
magnitudes  four,  ten  and  a  half,  and  eleven,  distances  36", 
p.  249°,  and  36",  p.  60°— the  ten-and-a-half-magnitude 
star  is  itself  double,  as  discovered  by  Burnham;  star  clus- 
ter No.  1030,  not  quite  as  broad  as  the  moon,  and  contain- 
ing some  stars  as  large  as  the  eleventh  magnitude;  and 
nebula  No.  1157,  the  so-called  "  Crab  nebula "  of  Lord 
Rosse,  which  our  glasses  will  show  only  as  a  misty  patch 
of  faint  light,  although  large  telescopes  reveal  in  it  a 
very  curious  structure. 

We  now  turn  to  the  cluster  of  circumpolar  constella- 
tions sometimes  called  the  Royal  Family,  in  allusion  to 
the  well-known  story  of  the  Ethiopian  king  Cepheus  and 
his  queen  Cassiopeia,  whose  daughter  Andromeda  was 
exposed  on  the  seashore  to  be  devoured  by  a  monster,  but 
who  was  saved  by  the  hero  Perseus.  All  these  mythologic 
personages  are  represented  in  the  constellations  that  we 


PISCES,  ARIES,  TAURUS,  AND  THE  NORTHERN  STARS    125 

are  about  to  study.*  We  begin  with  Andromeda  (map  No. 
24).  The  leading  star  a  marks  one  corner  of  the  great 
square  of  Pegasus.  The  first  star  of  telescopic  interest 
that  we  find  in  Andromeda  is  /A,  a  double  difficult  on  ac- 
count of  the  faintness  of  the  smaller  component.  The 
magnitudes  are  four  and  eleven,  distance  49",  p.  110°.  A 
few  degrees  north  of  /*  the  naked  eye  detects  a  glimmer- 
ing point  where  lies  the  Great  Nebula  in  Andromeda. 
This  is  indicated  on  the  map  by  the  number  116.  With 
either  of  our  three  telescopes  it  is  an  interesting  object, 
but  of  course  it  is  advisable  to  use  our  largest  glass  in 
order  to  get  as  much  light  as  possible.  All  that  we  can 
see  is  a  long,  shuttle-shaped  nebulous  object,  having  a 
brighter  point  near  the  center.  Many  stars  are  scattered 
over  the  field  in  its  neighborhood,  but  the  nebula  itself, 
although  its  spectrum  is  peculiar  in  resembling  that  of  a 
faint  star,  is  evidently  a  gaseous  or  at  any  rate  a  meteo- 
ritic  mass,  since  photographs  show  it  to  be  composed  of  a 
series  of  imperfectly  separated  spirals  surrounding  a  vast 
central  condensation.  This  peculiarity  of  the  Androm- 
eda nebula,  which  is  invisible  with  telescopes  although 
conspicuous  in  the  photographs,  has,  since  its  discovery 
a  few  years  ago,  given  a  great  impetus  to  speculation  con- 
cerning the  transformation  of  nebula  into  stars  and  star 
clusters.  No  one  can  look  at  a  good  photograph  of  this 
wonderful  phenomenon  without  noticing  its  resemblance 
to  the  ideal  state  of  things  which,  according  to  the  nebu- 
lar hypothesis,  must  once  have  existed  in  the  solar  system. 
It  is  to  be  remembered,  however,  that  there  is  probably 
sufficient  material  in  the  Andromeda  nebula  to  make  a 
system  many  times,  perhaps  hundreds  or  thousands  of 
times,  as  extensive  as  that  of  which  our  sun  is  the  center. 
If  one  contemplates  this  nebula  only  long  enough  to  get 

*  For  further  details  on  this  subject  see  Astronomy  with  an  Opera-glass. 


126 


PLEASURES  OF  THE  TELESCOPE 


a  clear  perception  of  the  fact  that  creation  was  not  ended 
when,  according  to  the  Mosaic  history,  God,  having  in  six 
days  finished  "  the  heavens  and  the  earth  and  all  the  host 
of  them,"  rested  from  all  his  work,  a  good  blow  will  have 
been  dealt  for  the  cause  of  truth.  Systems  far  vaster 
than  ours  are  now  in  the  bud,  and  long  before  they  have 
bloomed,  ambitious  man,  who  once  dreamed  that  all  these 


ASTEROPE  II 


TAYGETA* 


ALCYONE 

*    " 


ELECTRA  * 


THE  CHIEF  STARS  IN  THE  PLEIADES. 


things  were  created  to  serve  him,  will  probably  have  van- 
ished with  the  extinguishment  of  the  little  star  whose 
radiant  energy  made  his  life  and  his  achievements  briefly 
possible. 

In  August,  1885, -a  new  star  of  magnitude  six  and  a 
half  made  its  appearance  suddenly  near  the  center  of  the 
Andromeda  nebula.  Within  one  year  it  had  disappeared, 
having  gradually  dwindled  until  the  great  Washington 
telescope,  then  the  largest  in  use,  no  longer  showed  it. 
That  this  was  a  phenomenon  connected  with  the  nebula 
is  most  probable,  but  just  what  occurred  to  produce  it  no- 
body knows.  The  observed  appearances  might  have  been 


128  PLEASURES  OF  THE  TELESCOPE 

produced  by  a  collision,  and  no  better  hypothesis  has  yet 
been  suggested  to  account  for  them. 

Near  the  opposite  end  of  the  constellation  from  a  we 
find  the  most  interesting  of  triple  stars  in  7.  The  two 
larger  components  of  this  beautiful  star  are  of  magni- 
tudes three  and  six,  distance  10",  colors  golden  yellow  and 
deep  blue.  The  three-inch  shows  them  finely.  The  smaller 
star  is  itself  double,  its  companion  being  of  magnitude 
eight,  distance  when  discovered  in  1842  0.5",  color  bluish 
green.  A  few  years  ago  this  third  star  got  so  close  to  its 
primary  that  it  was  invisible  even  with  the  highest  powers 
of  the  great  Lick  telescope,  but  at  present  it  is  widening 
again.  In  October,  1893,  I  had  the  pleasure  of  looking 
at  7  Andromedse  with  the  Lick  telescope,  and  at  that  time 
it  was  possible  just  to  separate  the  third  star.  The 
angle  seemed  too  small  for  certain  measurement,  but 
a  single  setting  of  the  micrometer  by  Mr.  Barnard,  to 
whose  kindness  I  was  indebted  for  my  view  of  the  star, 
gave  0.17"  as  the  approximate  distance.  In  1900  the  dis- 
tance had  increased  to  0.4",  p.  115°.  The  brilliance  of 
color  contrast  between  the  two  larger  stars  of  7  Androm- 
eda3  is  hardly  inferior  to  that  exhibited  in  0  Cygni,  so 
that  this  star  may  be  regarded  as  one  of  the  most  pictur- 
esque of  stellar  objects  for  small  telescopes. 

Other  pleasing  objects  in  this  constellation  are  the 
binary  star  36,  magnitudes  six  and  six  and  a  half,  distance 
1",  p.  17° — the  two  stars  are  slowly  closing  and  the  five- 
inch  glass  is  required  to  separate  them:  the  richly  col- 
ored variable  B,  which  fades  from  magnitude  five  and  a 
half  to  invisibility,  and  then  recovers  its  light  in  a  period 
of  about  four  hundred  and  five  days;  and  the  bright  star 
cluster  457,  which  covers  a  space  about  equal  to  the  area 
of  the  full  moon. 

Just  south  of  the  eastern  end  of  Andromeda  is  the 


PISCES,  ARIES,  TAURUS,  AND  THE  NORTHERN  STARS    129 

small  constellation  Triangulum,  or  the  Triangles,  contain- 
ing two  interesting  objects.  One  of  these  is  the  beautiful 
little  double  6,  magnitudes  five  and  six,  distance  3.8", 
p.  77°,  colors  yellow  and  blue;  and  the  other,  the  nebula 
352,  which  equals  in  extent  the  star  cluster  in  Andromeda 
described  above,  but  nevertheless  appears  very  faint  with 
our  largest  glass.  Its  faintness,  however,  is  not  an  indi- 
cation of  insignificance,  for  to  very  powerful  'telescopes 
it  exhibits  a  wonderful  system  of  nuclei  and  spirals — an- 
other bit  of  chaos  that  is  yielding  by  age-long  steps  to  the 
influence  of  demiurgic  forces. 

A  richer  constellation  than  Andromeda,  both  for 
naked-eye  and  telescopic  observation,  is  Perseus,  which  is 
especially  remarkable  for  its  star  clusters.  Two  of  these, 
512  and  521,  constitute  the  celebrated  double  cluster, 
sometimes  called  the  Sword-hand  of  Perseus,  and  also  % 
Persei.  To  the  smallest  telescope  this  aggregation  of 
stars,  ranging  in  magnitude  from  six  and  a  half  to  four- 
teen, and  grouped  about  two  neighboring  centers,  pre- 
sents a  marvelous  appearance.  As  an  educative  object 
for  those  unaccustomed  to  celestial  observations  it  may 
be  compared  among  star  clusters  to  0  Cygni  among 
double  stars,  for  the  most  indifferent  spectator  is  struck 
with  wonder  in  viewing  it.  All  the  other  clusters  in 
Perseus  represented  on  the  map  are  worth  examining, 
although  none  of  them  calls  for  special  mention,  except 
perhaps  584,  where  we  may  distinguish  at  least  a  hundred 
separate  stars  within  an  area  less  than  one  quarter  as 
expansive  as  the  face  of  the  moon. 

Among  the  double  stars  of  Perseus  we  note  first  77, 
whose  components  are  of  magnitudes  four  and  eight,  dis- 
tance 28",  colors  white  and  pale  blue.  The  double  e  is 
especially  interesting  on  account  of  an  alleged  change  of 
color  from  blue  to  red  which  the  smaller  star  undergoes 


130  PLEASURES  OF  THE  TELESCOPE 

coincidently  with  a  variation  of  brightness.  The  mag- 
nitudes are  three  and  eight,  distance  9",  p.  9°.  An  inter- 
esting multiple  is  f,  two  of  whose  stars  at  least  we  can 
see.  The  magnitudes  are  three,  nine,  ten,  and  ten,  dis- 
tances 13",  p.  207°,  90",  and  112". 

The  chief  attraction  in  Perseus  is  the  changeful  and 
wonderful  /3,  or  Algol,  the  great  typical  star  among  the 
short-period  variables.  During  the  greater  part  of  its 
period  this  star  is  of  magnitude  two  and  two  tenths,  but 
for  a  very  short  time,  following  a  rapid  loss  of  light,  it 
remains  at  magnitude  three  and  seven  tenths.  The  differ- 
ence, one  magnitude  and  a  half,  corresponds  to  an  actual 
difference  in  brightness  in  the  ratio  of  3.75  to  1.  The 
entire  loss  of  light  during  the  declension  occupies  only 
four  hours  and  a  half.  The  star  remains  at  its  faintest 
for  a  few  minutes  only  before  a  perceptible  gain  of  light 
occurs,  and  the  return  to  maximum  is  as  rapid  as  was 
the  preceding  decline.  The  period  from  one  minimum  to 
the  next  is  two  days  twenty  hours  forty-eight  minutes 
fifty-three  seconds,  with  an  irregularity  amounting  to  a 
few  seconds  in  a  year.  The  Arabs  named  the  star  Algol, 
or  the  Demon,  on  account  of  its  eccentricity  which  did  not 
escape  their  attention;  and  when  Goodricke,  in  1782,  ap- 
plied a  scientific  method  of  observation  to  it,  the  real 
cause  of  its  variations  was  suggested  by  him,  but  his  ex- 
planation failed  of  general  acceptance  until  its  truth  was 
established  by  Prof.  E.  C.  Pickering  in  1880.  This  expla- 
nation gives  us  a  wonderful  insight  into  stellar  consti- 
tution. According  to  it,  Algol  possesses  a  companion  as 
large  as  the  sun,  but  invisible,  both  because  of  its  proxim- 
ity to  that  star  and  because  it  yields  no  light,  and  revolv- 
ing in  a  plane  horizontal  to  our  line  of  sight.  The  period 
of  revolution  is  identical  with  the  period  of  AlgoFs  cycle 
of  variation,  and  the  diminution  of  light  is  caused  by  the 


PISCES,  ARIES,  TAURUS,  AND  THE  NORTHERN  STARS    131 

interposition  of  the  dark  body  as  it  sweeps  along  that 
part  of  its  orbit  lying  between  our  point  of  view  and  the 
disk  of  Algol.  In  other  words,  once  in  every  two  days 
twenty  hours  and  forty-nine  minutes  Algol,  as  seen  from 
the  earth,  undergoes  a  partial  eclipse. 

In  consequence  of  the  great  comparative  mass  of  its 
dark  companion,  Algol  itself  moves  in  an  orbit  around 
their  common  center  with  a  velocity  quite  sufficient  to  be 
detected  by  the  shifting  of  the  lines  in  its  spectrum.  By 
means  of  data  thus  obtained  the  mass,  size,  and  distance 
apart  of  Algol  and  its  singular  comrade  have  been  in- 
ferred. The  diameter  of  Algol  is  believed  to  be  about 
1,125,000  miles,  that  of  the  dark  body  about  840,000  miles, 
and  the  mean  distance  from  center  to  center  3,230,000 
miles.  The  density  of  both  the  light  and  the  dark  star  is 
slight  compared  with  that  of  the  sun,  so  that  their  com- 
bined mass  is  only  two  thirds  as  great  as  the  sun's. 

Mention  has  been  made  of  a  slight  irregularity  in 
AlgoFs  period  of  variation.  Basing  his  calculations  upon 
this  inequality,  Dr.  Chandler  has  put  forward  the  hypoth- 
esis that  there  is  another  invisible  body  connected  with 
Algol,  and  situated  at  a  distance  from $t  of  about 
1,800,000,000  miles,  and  that  around  this  body,  which  is 
far  more  massive  than  the  others,  Algol  and  its  compan- 
ions revolve  in  a  period  of  one  hundred  and  thirty  years! 
Dr.  Chandler  has  earned  the  right  to  have  his  hypotheses 
regarded  with  respect,  even  when  they  are  as  extraor- 
dinary as  that  which  has  just  been  described.  It  needs  no 
indulgence  of  the  imagination  to  lend  interest  to  Algol; 
the  simple  facts  are  sufficient.  How  did  that  bright  star 
fall  in  with  its  black  neighbors?  Or  were  they  created 
together? 

Passing  to  the  region  covered  by  map  No.  25,  our  eyes 
are  caught  by  the  curious  figure,  formed  by  the  five  bright- 


132  PLEASURES  OF  THE  TELESCOPE 

est  stars  of  the  constellation  Cassiopeia,  somewhat  re- 
sembling the  letter  W.  Like  Perseus,  this  is  a  rich  con- 
stellation, both  in  star  clusters  and  double  stars.  Among 
the  latter  we  select  as  our  first  example  cr,  in  which  we 
find  a  combination  of  color  that  is  at  once  very  unusual 
and  very  striking — green  and  blue.  The  magnitudes  are 
five  and  seven,  distance  3",  p.  324°.  Another  beautiful 
colored  double  is  77,  whose  magnitudes  are  four  and  seven 
and  a  half,  distance  5",  p.  200°,  colors  white  and  purple. 
This  is  one  of  the  comparatively  small  number  of  stars 
the  measure  of  whose  distance  has  been  attempted,  and  a 
keen  sense  of  the  uncertainty  of  such  measures  is  con- 
veyed by  the  fact  that  authorities  of  apparently  equal 
weight  place  17  Cassiopeia  at  such  discordant  distances 
as  124,000,000,000,000  miles,  70,000,000,000,000  miles,  and 
42,000,000,000,000  miles.  It  will  be  observed  that  the  dif- 
ference between  the  greatest  and  the  least  of  these  esti- 
mates is  about  double  the  entire  distance  given  by  the 
latter.  The  same  thing  is  practically  true  of  the  various 
attempts  to  ascertain  the  distance  of  the  other  stars 
which  have  a  perceptible  parallax,  even  those  which  are 
evidently  the  nearest.  In  some  cases  the  later  measures 
increase  the  distance,  in  other  cases  they  diminish  it;  in 
no  case  is  there  anything  like  a  complete  accord.  Yet  of 
course  we  are  not  to  infer  that  it  is  hopeless  to  learn  any- 
thing about  the  distances  of  the  stars.  With  all  their 
uncertainties  and  disagreements  the  few  parallaxes  we 
possess  have  laid  a  good  foundation  for  a  knowledge  of 
the  dimensions  of  at  least  the  nearer  parts  of  the  universe. 
We  find  an  interesting  triple  in  1^,  the  magnitudes  of 
the  larger  components  being  four  and  a  half  and  eight  and 
a  half,  distance  30".  The  smaller  star  has  a  nine-and-a- 
half-magnitude  companion,  distance  3".  A  more  beauti- 
ful triple  is  i,  magnitudes  four,  seven,  and  eight,  distances 


134:  PLEASURES  OF  THE  TELESCOPE 

2",  p.  256°,  and  7.5",  p.  112°.  Cassiopeia  contains  many 
star  clusters,  three  of  which  are  indicated  in  the  map.  Of 
these  392  is  perhaps  the  most  interesting,  as  it  includes 
stars  of  many  magnitudes,  among- which  are  a  red  one 
of  the  eighth  magnitude,  and  a  ninth-magnitude  double 
whose  components  are  8"  apart.  Not  far  from  the  star  K 
we  find  the  spot  where  the  most  brilliant  temporary  star 
on  record  made  its  appearance  on  November  11,  1572.  Ty- 
cho  Brahe  studied  this  phenomenon  during  the  entire 
period  of  its  visibility,  which  lasted  until  March,  1574.  It 
burst  out  suddenly  with  overpowering  splendor,  far  out- 
shining every  fixed  star,  and  even  equaling  Venus  at  her 
brightest.  In  a  very  short  time  it  began  to  fade,  regu- 
larly diminishing  in  brightness,  and  at  the  same  time 
undergoing  changes  of  color,  ending  in  red,  until  it  disap- 
peared. It  has  never  been  seen  since,  and  the  suspicion 
once  entertained  that  it  was  a  variable  with  a  period  con- 
siderably exceeding  three  hundred  years  has  not  been  con- 
firmed. There  is  a  tenth-magnitude  star  near  the  place 
given  by  Tycho  as  that  occupied  by  the  stranger.  Many 
other  faint  stars  are  scattered  about,  however,  and  Ty- 
cho's  measures  were  not  sufficiently  exact  to  enable  us  to 
identify  the  precise  position  of  his  star.  If  the  phenome- 
non was  due  to  a  collision,  no  reappearance  of  the  star  is 
to  be  expected. 

Camelopardalus  is  a  very  inconspicuous  constellation, 
yet  it  furnishes  considerable  occupation  for  the  telescope. 
S  390,  of  magnitude  five,  has  a  companion  of  magnitude 
nine  and  a  half,  distance  15",  160°.  2  385,  also  of  the  fifth 
magnitude,  has  a  ninth-magnitude  companion,  distance 
only  2.4",  p.  160°.  According  to  some  observers,  the 
larger  star  is  yellow  and  the  smaller  white.  The  star  1  is 
a  very  pretty  double,  magnitudes  both  six,  distance  10.4". 
Its  neighbor  2  of  magnitude  six  has  an  eighth-magnitude 


PISCES,  ARIES,  TAURUS,  AND  THE  NORTHERN  STARS    135 

companion,  distance  1.7",  p.  278°.  The  star  7  of  mag- 
nitude five  is  also  double,  the  companion  of  magnitude 
eight  being  distant  only  1.2".  A  glance  at  star  cluster 
940,  which  shows  a  slight  central  condensation,  completes 
our  work  in  Camelopardalus,  and  we  turn  to  Ursa  Major, 
represented  in  map  No.  26.  Here  there  are  many  interest- 
ing doubles  and  triples.  Beginning  with  i  we  find  at  once 
occupation  for  our  largest  glass.  The  magnitudes  are 
three  and  ten,  distance  10",  p.  357°.  In  the  double  star  23 
the  magnitudes  are  four  and  nine,  distance  23",  p.  272°. 
A  more  pleasing  object  is  o-2,  a  greenish  fifth-magnitude 
star  which  has  an  eighth-magnitude  companion,  distance 
2.6",  p.  245°.  A  good  double  for  our  four-inch  glass  is  f, 
whose  magnitudes  are  four  and  five,  distance  1.87",  p. 
183°.  This  is  a  binary  with  a  period  of  revolution  of 
about  sixty  years,  and  is  interesting  as  the  first  binary 
star  whose  orbit  was  determined.  Savary  calculated  it  in 
1828.  Near  by  is  */,  a  difficult  double,  magnitudes  four 
and  ten  and  a  half,  distance  7",  p.  147°.  In  57  we  find 
again  an  easy  double  magnitudes  six  and  eight,  distance 
5.5",  p.  4°.  Another  similar  double  is  65,  magnitudes  six 
and  eight,  distance  3.9",  p.  38°.  A  third  star,  magnitude 
seven,  is  seen  at  a  distance  of  114"  from  the  primary. 

We  come  now  to  Ursa  Major's  principal  attraction  f, 
frequently  called  Mizar.  The  naked  eye  perceives  near  it 
a  smaller  star,  named  Alcor.  With  the  three-inch  glass 
and  a  medium  power  we  divide  Mizar  into  two  bright  stars 
brilliantly  contrasted  in  color,  the  larger  being  white  and 
the  smaller  blue-green.  Beside  Alcor,  several  fainter  stars 
are  seen  scattered  over  the  field  of  view,  and,  taken  all 
in  all,  there  are  very  few  equally  beautiful  sights  in  the 
starry  heavens.  The  magnitudes  of  the  double  are  three 
and  four,  distance  14.5",  p.  148°.  The  large  star  is  again 
double,  although  no  telescope  has  been  able  to  show  it  so, 


136  PLEASURES  OF  THE  TELESCOPE 

its  duplicity  being  revealed,  like  that  of  /?  AurigaB,  by  the 
periodical  splitting  of  the  lines  in  its  spectrum. 

Ursa  Major  contains  several  nebulae  which  may  be 
glimpsed  with  telescopes  of  moderate  dimensions.  An  in- 
teresting pair  of  these  objects,  both  of  which  are  included 
in  one  field  of  view,  is  formed  by  1949  and  1950.  The  first 
named  is  the  brighter  of  the  two,  its  nucleus  resembling  a 
faint  star.  The  nebula  2343  presents  itself  to  us  in  the 
form  of  a  faint,  hazy  star,  but  with  large  telescopes  its 
appearance  is  very  singular.  According  to  a  picture 
made  by  Lord  Rosse,  it  bears  no  little  resemblance  to  a 
skull,  there  being  two  symmetrically  placed  holes  in  it, 
each  of  which  contains  a  star. 

The  portion  of  Canes  Venatici,  represented  in  map  No. 
26,  contains  two  or  three  remarkable  objects.  2  1606  is  a 
close  double,  magnitudes  six  and  seven,  distance  1",  p. 
336°.  It  is  a  pretty  sight  with  the  five-inch.  The  double 
star  2  is  singular  in  that  its  larger  component  is  red  and 
its  smaller  blue;  magnitudes  six  and  eight,  distance 
11.4",  p.  260°.  Still  more  beautiful  is  12,  commonly  called 
Cor  Caroli.  This  double  is  wide,  and  requires  but  a  slight 
magnifying  power.  The  magnitudes  are  three  and  six, 
distance  20",  colors  white  or  light  yellow  and  blue.  The 
nebula  3572,  although  we  can  see  it  only  as  a  pair  of  misty 
specks,  is  in  reality  a  very  wonderful  object.  Lord  Rosse's 
telescope  has  revealed  in  it  a  complicated  spiral  struc- 
ture, recalling  the  photographs  of  the  Andromeda  nebula, 
and  indicating  that  stupendous  changes  must  be  in  pro- 
cess within  it,  although  our  records  of  observation  are 
necessarily  too  brief  to  bring  out  any  perceptible  altera- 
tion of  figure.  It  would  seem  that  the  astronomer  has,  of 
all  men,  the  best  reasons  for  complaining  of  the  brevity 
of  human  life. 

Lastly,  we  turn  to  Ursa  Minor  and  the  Pole  Star.     The 


URSA    MINOR 


CAMELOPARDALUS 


:ANES  VENATICI 


URSA    MAJOR 


LEO    MINOR 


MAP  No.  26. 


10 


138  PLEASURES  OF  THE  TELESCOPE 

latter  is  a  celebrated  double,  not  difficult,  except  with  a 
telescope  of  less  than  three  inches  aperture  in  the  hands 
of  an  inexperienced  observer.  The  magnitudes  are  two 
and  nine,  distance  18.5".  The  small  star  has  a  dull  blue 
color.  In  1899  it  was  discovered  by  spectroscopic  evi- 
dence that  the  Pole  Star  is  triple.  In  IT'  we  see  a  wide 
double,  magnitudes  six  and  seven,  distance  30",  p.  83°. 
This  completes  our  survey  of  the  starry  heavens. 


CHAPTEK    VIII 

SCENES   ON   THE   PLANETS 

"These  starry  globes  far  surpassed  the  earth  in  grandeur,  and  the  latter 
looked  so  diminutive  that  our  empire,  which  appeared  only  as  a  point  on  its  sur- 
face, awoke  my  pity." — CICERO,  THE  DREAM  OF  SCIPIO. 

ALTHOUGH  amateurs  have  played  a  conspicuous  part 
in  telescopic  discovery  among  the  heavenly  bodies,  yet 
every  owner  of  a  small  telescope  should  not  expect  to  at- 
tach his  name  to  a  star.  But  he  certainly  can  do  some- 
thing perhaps  more  useful  to  himself  and  his  friends;  he 
can  follow  the  discoveries  that  others,  with  better  appli- 
ances and  opportunities,  have  made,  and  can  thus  impart 
to  those  discoveries  that  sense  of  reality  which  only  comes 
from  seeing  things  with  one's  own  eyes.  There  are  hun- 
dreds of  things  continually  referred  to  in  books  and  writ- 
ings on  astronomy  which  have  but  a  misty  and  uncertain 
significance  for  the  mere  reader,  but  which  he  can  easily 
verify  for  himself  with  the  aid  of  a  telescope  of  four  or 
five  inches  aperture,  and  which,  when  actually  confronted 
by  the  senses,  assume  a  meaning,  a  beauty,  and  an  im- 
portance that  would  otherwise  entirely  have  escaped  him. 
Henceforth  every  allusion  to  the  objects  he  has  seen  is 
eloquent  with  intelligence  and  suggestion. 

Take,  for  instance,  the  planets  that  have  been  the  sub- 
ject of  so  many  observations  and  speculations  of  late 
years — Mars,  Jupiter,  Saturn,  Venus.  For  the  ordinary 
reader  much  that  is  said  about  them  makes  very  little  im- 

139 


140  PLEASURES  OF  THE  TELESCOPE 

pression  upon  his  mind,  and  is  almost  unintelligible.  He 
reads  of  the  "  snow  patches  "  on  Mars,  but  unless  he  has 
actually  seen  the  whitened  poles  ,Df  that  planet  he  can 
form  no  clear  image  in  his  mind  of  what  is  meant.  So  the 
"  belts  of  Jupiter  "  is  a  confusing  and  misleading  phrase 
for  almost  everybody  except  the  astronomer,  and  the 
rings  of  Saturn  are  beyond  comprehension  unless  they 
have  actually  been  seen. 

It  is  true  that  pictures  and  photographs  partially  sup- 
ply the  place  of  observation,  but  by  no  means  so  success- 
fully as  many  imagine.  The  most  realistic  drawings  and 
the  sharpest  photographs  in  astronomy  are  those  of  the 
moon,  yet  I  think  nobody  would  maintain  that  any  picture 
in  existence  is  capable  of  imparting  a  really  satisfactory 
visual  impression  of  the  appearance  of  the  lunar  globe. 
Nobody  who  has  not  seen  the  moon  with  a  telescope — it 
need  not  be  a  large  one — can  form  a  correct  and  definite 
idea  of  what  the  moon  is  like. 

The  satisfaction  of  viewing  with  one's  own  eyes  some 
of  the  things  the  astronomers  write  and  talk  about  is  very 
great,  and  the  illumination  that  comes  from  such  viewing 
is  equally  great.  Just  as  in  foreign  travel  the  actual  see- 
ing of  a  famous  city,  a  great  gallery  filled  with  master- 
pieces, or  a  battlefield  where  decisive  issues  have  been 
fought  out  illuminates,  for  the  traveler's  mind,  the  events 
of  history,  the  criticisms  of  artists,  and  the  occurrences  of 
contemporary  life  in  foreign  lands,  so  an  acquaintance 
with  the  sights  of  the  heavens  gives  a  grasp  on  astronom- 
ical problems  that  can  not  be  acquired  in  any  other  way. 
The  person  who  has  been  in  Rome,  though  he  may  be  no 
archaeologist,  gets  a  far  more  vivid  conception  of  a  new 
discovery  in  the  Forum  than  does  the  reader  who  has 
never  seen  the  city  of  the  Seven  Hills;  and  the  amateur 
who  has  looked  at  Jupiter  with  a  telescope,  though  he 


SCENES  ON  THE  PLANETS 


141 


may  be  no  astronomer,  finds  that  the  announcement  of 
some  change  among  the  wonderful  belts  of  that  cloudy 
planet  has  for  him  a  meaning  and  an  interest  in  which  the 
ordinary  reader  can  not  share. 

Jupiter  is  perhaps  the  easiest  of  all  the  planets  for  the 
amateur  observer.  A  three-inch  telescope  gives  beauti- 
ful views  of  the  great 
planet,  although  a  four- 
inch  or  a  five-inch  is 
of  course  better.  But 
there  is  no  necessity 
for  going  beyond  six 
inches'  aperture  in  any 
case.  For  myself,  I 
should  care  for  nothing 
better  than  my  Byrne 
five-inch  of  fifty  -  two 
inches'  focal  distance. 
With  such  a  glass 
more  details  are  visi- 
ble in  the  dark  belts 

and  along  the  bright  equatorial  girdle  than  can  be  correct- 
ly represented  in  a  sketch  before  the  rotation  of  the  planet 
has  altered  their  aspect,  while  the  shadows  of  the  satel- 
lites thrown  upon  the  broad  disk,  and  the  satellites  them- 
selves when  in  transit,  can  be  seen  sometimes  with  ex- 
quisite clearness.  The  contrasting  colors  of  various  parts 
of  the  disk  are  also  easily  studied  with  a  glass  of  four  or 
five  inches'  aperture. 

There  is  a  charm  about  the  great  planet  when  he  rides 
high  in  a  clear  evening  sky,  lording  it  over  the  fixed  stars 
with  his  serene,  unflickering  luminousness,  which  no  pos- 
sessor of  a  telescope  can  resist.  You  turn  the  glass  upon 
him  and  he  floats  into  the  field  of  view,  with  his  cortege  of 


JUPITER  SEEN  WITH  A  FIVE-INCH  TELESCOPE. 
Shadow  of  a  satellite  visible. 


142  PLEASURES  OF  THE  TELESCOPE 

satellites,  like  a  yellow-and-red  moon,  attended  by  four 
miniatures  of  itself.  You  instantly  comprehend  Jupiter's 
mastery  over  his  satellites — their  allegiance  is  evident. 
No  one  would  for  an  instant  mistake  them  for  stars  acci- 
dentally seen  in  the  same  field  of  view.  Although  it  re- 
quires a  very  large  telescope  to  magnify  their  disks  to 
measurable  dimensions,  yet  the  smallest  glass  differen- 
tiates them  at  once  from  the  fixed  stars.  There  is  some- 
thing almost  startling  in  their  appearance  of  companion- 
ship with  the  huge  planet — this  sudden  verification  to  your 
eyes  of  the  laws  of  gravitation  and  of  central  forces.  It 
is  easy,  while  looking  at  Jupiter  amid  his  family,  to  under- 
stand the  consternation  of  the  churchmen  when  Galileo's 
telescope  revealed  that  miniature  of  the  solar  system,  and 
it  is  gratifying  to  gaze  upon  one  of  the  first  battle  grounds 
whereon  science  gained  a  decisive  victory  for  truth. 

The  swift  changing  of  place  among  the  satellites,  as 
well  as  the  rapidity  of  Jupiter's  axial  rotation,  give  the 
attraction  of  visible  movement  to  the  Jovian  spectacle. 
The  planet  rotates  in  four  or  five  minutes  less  than  ten 
hours — in  other  words,  it  makes  two  turns  and  four  tenths 
of  a  third  turn  while  the  earth  is  rolling  once  upon  its 
axis.  A  point  on  Jupiter's  equator  moves  about  twenty- 
seven  thousand  miles,  or  considerably  more  than  the  en- 
tire circumference  of  the  earth,  in  a  single  hour.  The 
effect  of  this  motion  is  clearly  perceptible  to  the  observer 
with  a  telescope  on  account  of  the  diversified  markings 
and  colors  of  the  moving  disk,  and  to  watch  it  is  one  of 
the  greatest  pleasures  that  the  telescope  affords. 

It  would  be  possible,  when  the  planet  is  favorably  situ- 
ated, to  witness  an  entire  rotation  of  Jupiter  in  the  course 
of  one  night,  but  the  beginning  and  end  of  the  observation 
would  be  more  or  less  interfered  with  by  the  effects  of 
low  altitude,  to  say  nothing  of  the  tedium  of  so  long  a 


SCENES  ON  THE  PLANETS  143 

vigil.  But  by  looking  at  the  planet  for  an  hour  at  a  time 
in  the  course  of  a  few  nights  every  side  of  it  will  have 
been  presented  to  view.  Suppose  the  first  observation  is 
made  between  nine  and  ten  o'clock  on  any  night  which 
may  have  been  selected.  Then  on  the  following  night  be- 
tween ten  and  eleven  o'clock  Jupiter  will  have  made  two 
and  a  half  turns  upon  his  axis,  and  the  side  diametrically 
opposite  to  that  seen  on  the  first  night  will  be  visible.  On 
the  third  night  between  eleven  and  twelve  o'clock  Jupiter 
will  have  performed  five  complete  rotations,  and  the  side 
originally  viewed  will  be  visible  again. 

Owing  to  the  rotundity  of  the  planet,  only  the  central 
part  of  the  disk  is  sharply  defined,  and  markings  which 
can  be  easily  seen  when  centrally  located  become  indis- 
tinct or  disappear  altogether  when  near  the  limb.  Ap- 
proach to  the  edge  of  the  disk  also  causes  a  foreshorten- 
ing which  sometimes  entirely  alters  the  aspect  of  a  mark- 
ing. It  is  advisable,  therefore,  to  confine  the  attention 
mainly  to  -the  middle  of  the  disk.  As  time  passes,  clearly 
defined  markings  on  or  between  the  cloudy  belts  will  be 
seen  to  approach  the  western  edge  of  the  disk,  gradually 
losing  their  distinctness  and  altering  their  appearance, 
while  from  the  region  of  indistinct  definition  near  the 
eastern  edge  other  markings  slowly  emerge  and  advance 
toward  the  center,  becoming  sharper  in  outline  and  more 
clearly  defined  in  color  as  they  swing  into  view. 

Watching  these  changes,  the  observer  is  carried  away 
by  the  reflection  that  he  actually  sees  the  turning  of  an- 
other distant  world  upon  its  axis  of  rotation,  just  as  he 
might  view  the  revolving  earth  from  a  standpoint  on  the 
moon.  Belts  of  reddish  clouds,  many  thousands  of  miles 
across,  are  stretched  along  on  each  side  of  the  equator 
of  the  great  planet  he  is  watching;  the  equatorial  belt 
itself,  brilliantly  lemon-hued,  or  sometimes  ruddy,  is  di- 


144 


PLEASURES  OF  THE  TELESCOPE 


versified  with  white  globular  and  balloon-shaped  masses, 
which   almost   recall   the   appearance   of   summer   cloud 


I W 


ECLIPSES  AND  TRANSITS  OF  JUPITER'S  SATELLITES. 
Satellite  I  and  the  shadow  of  III  are  seen  in  transit.     IV  is  about  to  be  eclipsed. 

domes  hanging  over  a  terrestrial  landscape,  while  toward 
the  poles  shadowy  expanses  of  gradually  deepening  blue 


SCENES  ON  THE  PLANETS  145 

or  blue-gray  suggest  the  comparative  coolness  of  those 
regions  which  lie  always  under  a  low  sun. 

After  a  few  nights'  observation  even  the  veriest  ama- 
teur finds  himself  recognizing  certain  shapes  or  appear- 
ances— a  narrow  dark  belt  running  slopingly  across  the 
equator  from  one  of  the  main  cloud  zones  to  the  other, 
or  a  rift  in  one  of  the  colored  bands,  or  a  rotund  white 
mass  apparently  floating  above  the  equator,  or  a  broad 
scallop  in  the  edge  of  a  belt  like  that  near  the  site  of  the 
celebrated  "  red  spot,"  whose  changes  of  color  and  aspect 
since  its  first  appearance  in  1878,  together  with  the  light 
it  has  thrown  on  the  constitution  of  Jupiter's  disk,  have 
all  but  created  a  new  Jovian  literature,  so  thoroughly  and 
so  frequently  have  they  been  discussed. 

And,  having  noticed  these  recurring  features,  the  ob- 
server will  begin  to  note  their  relations  to  one  another, 
and  will  thus  be  led  to  observe  that  some  of  them  gradu- 
ally drift  apart,  while  others  drift  nearer;  and  after  a 
time,  without  any  aid  from  books  or  hints  from  observa- 
tories, he  will  discover  for  himself  that  there  is  a  law  gov- 
erning the  movements  on  Jupiter's  disk.  Upon  the  whole 
he  will  find  that  the  swiftest  motions  are  near  the  equator, 
and  the  slowest  near  the  poles,  although,  if  he  is  per- 
sistent and  has  a  good  eye  and  a  good  instrument,  he  will 
note  exceptions  to  this  rule,  probably  arising,  as  Pro- 
fessor Hough  suggests,  from  differences  of  altitude  in  Jupi- 
ter's atmosphere.  Finally,  he  will  conclude  that  the  co- 
lossal globe  before  him  is,  exteriorly  at  least,  a  vast  ball 
of  clouds  and  vapors,  subject  to  tremendous  vicissitudes, 
possibly  intensely  heated,  and  altogether  different  in  its 
physical  constitution,  although  made  up  of  similar  ele- 
ments, from  the  earth.  Then,  if  he  chooses,  he  can  sail  off 
into  the  delightful  cloud-land  of  astronomical  speculation, 
and  make  of  the  striped  and  spotted  sphere  of  Jove  just 


146  PLEASURES  OF  THE  TELESCOPE 

such  a  world  as  may  please  his  fancy — for  a  world  of  some 
kind  it  certainly  is. 

For  many  observers  the  satellites  of  Jupiter  possess 
even  greater  attractions  than  the  gigantic  ball  itself.  As 
I  have  already  remarked,  their  movements  are  very  notice- 
able and  lend  a  wonderful  animation  to  the  scene.  Al- 
though they  bear  classical  names,  they  are  almost  univer- 
sally referred  to  by  their  Roman  numbers,  beginning  with 
the  innermost,  whose  symbol  is  I,  and  running  outward  in 
regular  order  II,  III,  and  IV.*  The  minute  satellite  much 
nearer  to  the  planet  than  any  of  the  others,  which  Mr. 
Barnard  discovered  with  the  Lick  telescope  in  1892,  is 
called  the  fifth,  although  in  the  order  of  distance  it  would 
be  the  first.  In  size  and  importance,  however,  it  can  not 
rank  with  its  comparatively  gigantic  brothers.  Of  course, 
no  amateur's  telescope  can  afford  the  faintest  glimpse 
of  it. 

Satellite  I,  situated  at  a  mean  distance  of  261,000  miles 
from  Jupiter's  center — about  22,000  miles  farther  than  the 
moon  is  from  the  earth — is  urged  by  its  master's  overpow- 
ering attraction  to  a  speed  of  320  miles  per  minute,  so 
that  it  performs  a  complete  revolution  in  about  forty-two 
hours  and  a  half.  The  others,  of  course,  move  more 
slowly,  but  even  the  most  distant  performs  its  revolution 
in  several  hours  less  than  sixteen  days.  The  plane  of 
their  orbits  is  presented  edgewise  toward  the  earth,  from 
which  it  follows  that  they  appear  to  move  back  and  forth 
nearly  in  straight  lines,  some  apparently  approaching  the 
planet,  while  others  are  receding  from  it.  The  changes  in 
their  relative  positions,  which  can  be  detected  from  hour 
to  hour,  are  very  striking  night  after  night,  and  lead  to  a 
great  variety  of  arrangements  always  pleasing  to  the  eye. 

*  Their  names,  in  the  same  order  as  their  numbers,  are  lo,  Europa,  Gany- 
mede, and  Callisto. 


SCENES  ON  THE  PLANETS  147 

The  most  interesting  phenomena  that  they  present 
are  their  transits  and  those  of  their  round,  black  shadows 
across  the  face  of  the  planet;  their  eclipses  by  the 
planet's  shadow,  when  they  disappear  and  afterward  re- 
appear with  astonishing  suddenness;  and  their  occulta- 
tions  by  the  globe  of  Jupiter.  Upon  the  whole,  the  most 
interesting  thing  for  the  amateur  to  watch  is  the  passage 
of  the  shadows  across  Jupiter.  The  distinctness  with 
which  they  can  be  seen  when  the  air  is  steady  is  likely  to 
surprise,  as  it  is  certain  to  delight,  the  observer.  When 
it  falls  upon  a  light  part  of  the  disk  the  shadow  of  a  satel- 
lite is  as  black  and  sharply  outlined  as  a  drop  of  ink;  on  a 
dark-colored  belt  it  can  not  so  easily  be  seen. 

It  is  more  difficult  to  see  the  satellites  themselves  in 
transit.  There  appears  to  be  some  difference  among 
them  as  to  visibility  in  such  circumstances.  Owing  to 
their  luminosity  they  are  best  seen  when  they  have  a  dark 
belt  for  a  background,  and  are  least  easily  visible  when 
they  appear  against  a  bright  portion  of  the  planet.  Every 
observer  should  provide  himself  with  a  copy  of  the  Ameri- 
can Ephemeris  for  the  current  year,  wherein  he  will  find 
all  the  information  needed  to  enable  him  to  identify  the 
various  satellites  and  to  predict,  by  turning  Washington 
mean  time  into  his  own  local  time,  the  various  phenomena 
of  the  transits  and  eclipses. 

While  a  faithful  study  of  the  phenomena  of  Jupiter  is 
likely  to  lead  the  student  to  the  conclusion  that  the  great- 
est planet  in  our  system  is  not  a  suitable  abode  for  life, 
yet  the  problem  of  its  future,  always  fascinating  to  the 
imagination,  is  open;  and  whosoever  may  be  disposed  to 
record  his  observations  in  a  systematic  manner  may  at 
least  hope  to  render  aid  in  the  solution  of  that  problem. 

Saturn  ranks  next  to  Jupiter  in  attractiveness  for  the 
observer  with  a  telescope.  The  rings  are  almost  as  mysti- 


PLEASURES  OF  THE  TELESCOPE 

fying  to-day  as  they  were  in  the  time  of  Herschel.  There 
is  probably  no  single  telescopic  view  that  can  compare  in 
the  power  to  excite  wonder  with  that  of  Saturn  when  the 
ring  system  is  not  so  widely  opened"  but  that  both  poles  of 
the  planet  project  beyond  it.  One  returns  to  it  again  and 

again  with  unflagging  interest, 
and  the  beauty  of  the  spec- 
tacle quite  matches  its  singu- 
larity. When  Saturn  is  in 
view  the  owner  of  a  telescope 
may  become  a  recruiting  offi- 
<*r  for  astronomy  by  simply 
inviting  his  friends  to  gaze 

at  the  wonderful  planet.  The  silvery  color  of  the  ball, 
delicately  chased  with  half-visible  shadings,  merging  one 
into  another  from  the  bright  equatorial  band  to  the  bluish 
polar  caps;  the  grand  arch  of  the  rings,  sweeping  across 
the  planet  with  a  perceptible  edging  of  shadow;  their 
sudden  disappearance  close  to  the  margin  of  the  ball, 
where  they  go  behind  it  and  fall  straightway  into  night; 
the  manifest  contrast  of  brightness,  if  not  of  color,  be- 
tween the  two  principal  rings;  the  fine  curve  of  the  black 
line  marking  the  1,600-mile  gap  between  their  edges— 
these  are  some  of  the  elements  of  a  picture  that  can  never 
fade  from  the  memory  of  any  one  who  has  once  beheld  it 
in  its  full  glory. 

Saturn's  moons  are  by  no  means  so  interesting  to 
watch  as  are  those  of  Jupiter.  Even  the  effect  of  their 
surprising  number  (raised  to  nine  by  Professor  Pickering's 
discovery  in  1899  of  a  new  one  which  is  almost  at  the  limit 
of  visibility,  and  was  found  only  with  the  aid  of  pho- 
tography) is  lost,  because  most  of  them  are  too  faint  to 
be  seen  with  ordinary  telescopes,  or,  if  seen,  to  make  any 
notable  impression  upon  the  eye.  The  two  largest — Titan 


SCENES  ON  THE  PLANETS  149 

and  Japetus — are  easily  found,  and  Titan  is  conspicuous, 
but  they  give  none  of  that  sense  of  companionship  and 
obedience  to  a  central  authority  which  strikes  even  the 
careless  observer  of  Jupiter's  system.  This  is  owing 


POLAR  VIEW  OF  SATURN'S  SYSTEM. 

The  orbits  of  the  five  nearest  satellites  are  shown.    The  dotted  line  outside  the  rings 
shows  Roche's  limit. 

partly  to  their  more  deliberate  movements  and  partly  to 
the  inclination  of  the  plane  of  their  orbits,  which  seldom 
lies  edgewise  toward  the  earth. 

But  the  charm  of  the  peerless  rings  is  abiding,  and  the 
interest  of  the  spectator  is  heightened  by  recalling  what 


150  PLEASURES  OF  THE  TELESCOPE 

science  has  recently  established  as  to  their  composition. 
It  is  marvelous  to  think,  while  looking  upon  their  broad, 
level  surfaces — as  smooth,  apparently,  as  polished  steel, 
though  thirty  thousand  miles  across — that  they  are  in 
reality  vast  circling  currents  of  meteoritic  particles  or 
dust,  through  which  run  immense  waves,  condensation 
and  rarefaction  succeeding  one  another  as  in  the  undula- 
tions of  sound.  Yet,  with  all  their  inferential  tumult, 
they  may  actually  be  as  soundless  as  the  depths  of  inter- 
stellar space,  for  Struve  has  shown  that  those  spectacu- 
lar rings  possess  no  appreciable  mass,  and,  viewed  from 
Saturn  itself,  their  (to  us)  gorgeous  seeming  bow  may 
appear  only  as  a  wreath  of  shimmering  vapor  spanning 
the  sky  and  paled  by  the  rivalry  of  the  brighter  stars. 

In  view  of  the  theory  of  tidal  action  disrupting  a  satel- 
lite within  a  critical  distance  from  the  center  of  its  pri- 
mary, the  thoughtful  observer  of  Saturn  will  find  himself 
wondering  what  may  have  been  the  origin  of  the  rings. 
The  critical  distance  referred  to,  and  which  is  known  as 
Roche's  limit,  lies,  according  to  the  most  trustworthy  esti- 
mates, just  outside  the  outermost  edge  of  the  rings.  It 
follows  that  if  the  matter  composing  the  rings  were  col- 
lected into  a  single  body  that  body  would  inevitably  be 
torn  to  pieces  and  scattered  into  rings;  and  so,  too,  if  in- 
stead of  one  there  were  several  or  many  bodies  of  consid- 
erable size  occupying  the  place  of  the  rings,  all  of  these 
bodies  would  be  disrupted  and  scattered.  If  one  of  the 
present  moons  of  Saturn — for  instance,  Mimas,  the  inner- 
most hitherto  discovered — should  wander  within  the 
magic  circle  of  Roche's  limit  it  would  suffer  a  similar  fate, 
and  its  particles  would  be  disseminated  among  the  rings. 
One  can  hardly  help  wondering  whether  the  rings  have 
originated  from  the  demolition  of  satellites — Saturn  de- 
vouring his  children,  as  the  ancient  myths  represent,  and 


SCENES  ON  THE  PLANETS  151 

encircling  himself,  amid  the  fury  of  destruction,  with  the 
dust  of  his  disintegrated  victims.  At  any  rate,  the  ama- 
teur student  of  Saturn  will  find  in  the  revelations  of  his 
telescope  the  inspirations  of  poetry  as  well  as  those  of 
science,  and  the  bent  of  his  mind  will  determine  which  he 
shall  follow. 

Professor  Pickering's  discovery  of  a  ninth  satellite  of 
Saturn,  situated  at  the  great  distance  of  nearly  eight  mil- 
lion miles  from  the  planet,  serves  to  call  attention  to  the 
vastness  of  the  "  sphere  of  activity "  over  which  the 
ringed  planet  reigns.  Surprising  as  the  distance  of  the 
new  satellite  appears  when  compared  with  that  of  our 
moon,  it  is  yet  far  from  the  limit  where  Saturn's  control 
ceases  and  that  of  the  sun  becomes  predominant.  That 
limit,  according  to  Prof.  Asaph  HalPs  calculation,  is 
nearly  30,000,000  miles  from  Saturn's  center,  while  if  our 
moon  were  removed  to  a  distance  a  little  exceeding 
500,000  miles  the  earth  would  be  in  danger  of  losing  its 
satellite  through  the  elopement  of  Artemis  with  Apollo. 

Although,  as  already  remarked,  the  satellites  of  Sat- 
urn are  not  especially  interesting  to  the  amateur  tele- 
scopist,  yet  it  may  be  well  to  mention  that,  in  addition  to 
Titan  and  Japetus,  the  satellite  named  Khea,  the  fifth  in 
order  of  distance  from  the  planet,  is  not  a  difficult  object 
for  a  three-  or  four-inch  telescope,  and  two  others  consid- 
erably fainter  than  Rhea — Dione  (the  fourth)  and  Tethys 
(the  third) — may  be  seen  in  favorable  circumstances.  The 
others — Mimas  (the  first),  Enceladus  (the  second),  and 
Hyperion  (the  seventh) — are  beyond  the  reach  of  all  but 
large  telescopes.  The  ninth  satellite,  which  has  received 
the  name  of  Phoebe,  is  much  fainter  than  any  of  the 
others,  its  stellar  magnitude  being  reckoned  by  its  discov- 
erer at  about  15.5. 

Mars,  the  best  advertised  of  all  the  planets,  is  nearly 


J52 


PLEASURES  OF  THE  TELESCOPE 


the  least  satisfactory  to  look  at  except  during  a  favorable 
opposition,  like  those  of  1877  and  1892,  when  its  compara- 
tive nearness  to  the  earth  renders  some  of  its  character- 
istic features  visible  in  a  small  telescope.  The  next  favor- 
able opposition  will  occur  in  1907. 

When  well  seen  with  an  ordinary  telescope,  say  a  four- 
or  five-inch  glass,  Mars  shows  three  peculiarities  that  may 
be  called  fairly  conspicuous — viz.,  its  white  polar  cap,  its 
general  reddish,  or  orange-yellow,  hue,  and  its  dark  mark- 
ings, one  of  the  clearest  of  which  is  the  so-called  Syrtis 
Major,  or,  as  it  was  once  named  on  account  of  its  shape, 
"  Hourglass  Sea."  Other  dark  expanses  in  the  southern 
hemisphere  are  not  difficult  to  be  seen,  although  their  out- 
lines are  more  or  less  misty  and  indistinct.  The  gradual 
diminution  of  the  polar  cap,  which  certainly  behaves  in  this 
respect  as  a  mass  of  snow  and  ice  would  do,  is  a  most  in- 
teresting spectacle.  As 
summer  advances  in  the 
southern  hemisphere  of 
Mars,  the  white  circular 
patch  surrounding  the 
pole  becomes  smaller, 
night  after  night,  until 
it  sometimes  disappears 
entirely  even  from  the 
ken  of  the  largest  tele- 
scopes. At  the  same 
time  the  dark  expanses 
become  more  distinct,  as 
if  the  melting  of  the 

polar  snows  had  supplied  them  with  a  greater  depth  of 
water,  or  the  advance  of  the  season  had  darkened  them 
with  a  heavier  growth  of  vegetation. 

The  phenomena  mentioned  above  are  about  all  that  a 


MARS  SEEN  WITH  A  FIVE-INCH  TELESCOPE. 


SCENES  ON  THE  PLANETS 


153 


small  telescope  will  reveal.  Occasionally  a  dark  streak, 
which  large  instruments  show  is  connected  with  the  mys- 
terious system  of  "  canals,"  can  be  detected,  but  the  "  ca- 
nals "  themselves  are  far  beyond  the  reach  of  any  tele- 
scope except  a  few  of  the  giants  handled  by  experienced 
observers.  The  conviction  which  seems  to  have  forced  its 
way  into  the  minds  even  of  some  conservative  astrono- 
mers, that  on  Mars  the  conditions,  to  use  the  expression 
of  Professor  Young,  "  are  more  nearly  earthlike  than  on 
any  other  of  the  heavenly  bodies  which  we  can  see  with 
our  present  telescopes,"  is  sufficient  to  make  the  planet  a 
center  of  undying  inter- 
est notwithstanding  the 
difficulties  with  which 
the  amateur  is  confront- 
ed in  his  endeavors  to 
see  the  details  of  its 
markings. 

In  Venus  "  the  fatal 
gift  of  beauty  "  may  be 
said,  as  far  as  our  obser- 
vations are  concerned, 
to  be  matched  by  the 
equally  fatal  gift  of 
brilliance.  Whether  it 
be  due  to  atmospheric 
reflection  alone  or  to 

the  prevalence  of  clouds,  Venus  is  so  bright  that  consid- 
erable doubt  exists  as  to  the  actual  visibility  of  any  per- 
manent markings  on  her  surface.  The  detailed  representa- 
tions of  the  disk  of  Venus  by  Mr.  Percival  Lowell,  showing 
in  some  respects  a  resemblance  to  the  stripings  of  Mars, 
can  not  yet  be  accepted  as  decisive.  More  experienced 

astronomers  than  Mr.  Lowell  have  been  unable  to  see  at 
11 


THE  ILLUMINATION  OP  VENUS'S  ATMOSPHERE  AT  THE 

BEGINNING  OF  HER  TRANSIT  ACROSS  THE  SUN. 


154  PLEASURES  OF  THE  TELESCOPE 

all  things  which  he  draws  with  a  fearless  and  unhesitating 
pencil.  That  there  are  some  shadowy  features  of  the 
planet's  surface  to  be  seen  in  favourable  circumstances  is 
probable,  but  the  time  for  drawing'a  "  map  of  Venus  "  has 
not  yet  come. 

The  previous  work  of  Schiaparelli  lends  a  certain  de- 
gree of  probability  to  Mr.  Lowell's  observations  on  the 
rotation  of  Venus.  This  rotation,  according  to  the  origi- 
nal announcement  of  Schiaparelli,  is  probably  performed 
in  the  same  period  as  the  revolution  around  the  sun.  In 
other  words,  Venus,  if  Schiaparelli  and  Lowell  are  right, 
always  presents  the  same  side  to  the  sun,  possessing,  in 
consequence,  a  day  hemisphere  and  a  night  hemisphere 
which  never  interchange  places.  This  condition  is  so  an- 
tagonistic to  all  our  ideas  of  what  constitutes  habitability 
for  a  planet  that  one  hesitates  to  accept  it  as  proved,  and 
almost  hopes  that  it  may  turn  out  to  have  no  real  exist- 
ence. Venus,  as  the  twin  of  the  earth  in  size,  is  a  planet 
which  the  imagination,  warmed  by  its  sunny  aspect,  would 
fain  people  with  intelligent  beings  a  little  fairer  than  our- 
selves; but  how  can  such  ideas  be  reconciled  with  the  pic- 
ture of  a  world  one  half  of  which  is  subjected  to  the  merci- 
less rays  of  a  never-setting  sun,  while  the  other  half  is 
buried  in  the  fearful  gloom  and  icy  chill  of  unending 
night? 

Any  amateur  observer  who  wishes  to  test  his  eyesight 
and  his  telescope  in  the  search  of  shades  or  markings  on 
the  disk  of  Venus  by  the  aid  of  which  the  question  of  its 
rotation  may  finally  be  settled  should  do  his  work  while 
the  sun  is  still  above  the  horizon.  Schiaparelli  adopted 
that  plan  years  ago,  and  others  have  followed  him  with 
advantage.  The  diffused  light  of  day  serves  to  take  off 
the  glare  which  is  so  serious  an  obstacle  to  the  successful 
observation  of  Venus  when  seen  against  a  dark  sky. 


SCENES  ON  THE  PLANETS  155 

Knowing  the  location  of  Venus  in  the  sky,  which  can  be 
ascertained  from  the  Ephemeris,  the  observer  can  find  it 
by  day.  If  his  telescope  is  not  permanently  mounted  and 
provided  with  "  circles  "  this  may  not  prove  an  easy  thing 
to  do,  yet  a  little  perseverance  and  ingenuity  will  effect  it. 
One  way  is  to  find,  with  a  star  chart,  some  star  whose 
declination  is  the  same,  or  verv  nearly  the  same,  as  that  of 
Venus,  and  which  crosses  the  meridian  say  twelve  hours 
ahead  of  her.  Then  set  the  telescope  upon  that  star, 
when  it  is  on  the  meridian  at  night,  and  leave  it  there,  and 
the  next  day,  twelve  hours  after  the  star  crossed  the  me- 
ridian, look  into  your  telescope  and  you  will  see  Venus,  or, 
if  not,  a  slight  motion  of  the  tube  will  bring  her  into  view. 

For  many  amateurs  the  phases  of  Venus  will  alone 
supply  sufficient  interest  for  telescopic  observation.  The 
changes  in  her  form,  from  that  of  a  round  full  moon  when 
she  is  near  superior  conjunction  to  the  gibbous,  and  finally 
the  half-moon  phase  as  she  approaches  her  eastern  elonga- 
tion, followed  by  the  gradually  narrowing  and  lengthen- 
ing crescent,  until  she  is  a  mere  silver  sickle  between  the 
sun  and  the  earth,  form  a  succession  of  delightful  pictures. 

Not  very  much  can  be  said  for  Mercury  as  a  telescopic 
object.  The  little  planet  presents  phases  like  those  of 
Venus,  and,  according  to  Schiaparelli  and  Lowell,  it  re- 
sembles Venus  in  its  rotation,  keeping  always  the  same 
side  to  the  sun.  In  fact,  Schiaparelli's  discovery  of  this 
peculiarity  in  the  case  of  Mercury  preceded  the  similar 
discovery  in  the  case  of  Venus.  There  are  markings  on 
Mercury  which  have  reminded  some  astronomers  of  the 
moon,  and  there  are  reasons  for  thinking  that  the  planet 
can  not  be  a  suitable  abode  for  living  beings,  at  least  for 
beings  resembling  the  inhabitants  of  the  earth. 

Uranus  and  Neptune  are  too  far  away  to  present  any 
attraction  for  amateur  observers. 


CHAPTER    IX 

THE    MOUNTAINS    AND    PLAINS    OF   THE    MOON,    AND   THE 
SPECTACLES    OF   THE    SUN 

"...  the  Moon,  whose  orb 
The  Tuscan  artist  views  through  optic  glass 
At  evening  from  the  top  of  Fesole, 
Or  in  Valdarno,  to  descry  new  lands, 
Rivers  or  mountains  in  her  spotty  globe. " — PARADISE  LOST. 

THE  moon  is  probably  the  most  interesting  of  all  tele- 
scopic objects.  This  arises  from  its  comparative  near- 
ness to  the  earth.  A  telescope  magnifying  1,000  diam- 
eters brings  the  moon  within  an  apparent  distance  of 
less  than  240  miles.  If  telescopes  are  ever  made  with 
a  magnifying  power  of  10,000  diameters,  then,  provided 
that  atmospheric  difficulties  can  be  overcome,  we  shall 
see  the  moon  as  if  it  were  only  about  twenty  miles  off,  and 
a  sensitive  astronomer  might  be  imagined  to  feel  a  little 
hesitation  about  gazing  so  closely  at  the  moon — as  if  he 
were  peering  into  a  neighbor  world's  window. 

But  a  great  telescope  and  a  high  magnifying  power  are 
not  required  to  interest  the  amateur  astronomer  in  the 
study,  of  the  moon.  Our  three-inch  telescope  is  amply 
sufficient  to  furnish  us  with  entertainment  for  many  an 
evening  while  the  moon  is  running  through  its  phases, 
and  we  shall  find  delight  in  frequently  changing  the  mag- 
nifying power  as  we  watch  the  lunar  landscapes,  because 
every  change  will  present  them  in  a  different  aspect. 

It  should  be  remembered  that  a  telescope,  unless  a  ter- 
restrial eyepiece  or  prism  is  employed,  reverses  such  an 

156 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         157 

object  as  the  moon  top  for  bottom.  Accordingly,  if  the 
moon  is  on  or  near  the  meridian  when  the  observations 
are  made,  we  shall  see  the  north  polar  region  at  the 
bottom  and  the  south  polar  region  at  the  top.  In  other 
words,  the  face  of  the  moon  as  presented  in  the  telescope 
will  be  upside  down,  north  and  south  interchanging  places 
as  compared  with  their  positions  in  a  geographical  map. 
But  east  and  west  remain  unaltered  in  position,  as  com- 
pared with  such  a  map — i.  e.,  the  eastern  hemisphere  of 
the  moon  is  seen  on  the  right  and  the  western  hemisphere 
on  the  left.  It  is  the  moon's  western  edge  that  catches 
the  first  sunlight  when  "  new  moon  "  begins,  and,  as  the 
phase  increases,  passing  into  "  first  quarter  "  and  from 
that  to  "  full  moon,"  the  illumination  sweeps  across  the 
disk  from  west  to  east. 

The  narrow  sickle  of  the  new  moon,  hanging  above  the 
sunset,  is  a  charming  telescopic  sight.  Use  a  low  power, 
and  observe  the  contrast  between  the  bright,  smooth 
round  of  the  sunward  edge,  which  has  almost  the  polish 
of  a  golden  rim,  and  the  irregular  and  delicately  shaded 
inner  curve,  where  the  adjacent  mountains  and  plains 
picturesquely  reflect  or  subdue  the  sunshine.  While  the 
crescent  grows  broader  new  objects  are  continually  com- 
ing into  view  as  the  sun  rises  upon  them,  until  at  length 
one  of  the  most  conspicuous  and  remarkable  of  the  lunar 
"  seas,"  the  Mare  Crisium,  or  Sea  of  Crises,  lies  fully  dis- 
played amid  its  encircling  peaks,  precipices,  and  craters. 
The  Mare  Crisium  is  all  in  the  sunlight  between  the  third 
and  fourth  day  after  "  new  moon."  It  is  about  350  by  280 
miles  in  extent,  and  if  ever  filled  with  water  must  have 
been  a  very  deep  sea,  since  its  arid  bed  lies  at  a  great  but 
not  precisely  ascertained  depth  below  the  general  level 
of  the  moon.  There  are  a  few  small  craters  on  the  floor  of 
the  Mare  Crisium^  the  largest  bearing  the  name  of  Picard, 


158 


PLEASURES  OF  THE  TELESCOPE 


and  its  borders  are  rugged  with  mountains.  On  the 
southwestern  side  is  a  lofty  promontory,  11,000  feet  in 
height,  called  Cape  Agarum.  At  the  middle  of  the  east- 
ern side  a  kind  of  bay  opens  deep  in  the  mountains,  whose 


«    &         ILssV 
Fir  micas •  }     *>  \ 

U  J^Av 


8  >&'@ 

^Taruntius    MARE          ® 

TRANQUILITATIS 

» 


^  MARE 

'luut  Caesar 
^         VAPOKUM 


LUNAR  CHART  No.  1,  NORTHWEST  QUARTER. 


range  here  becomes  very  narrow.  Southeast  of  this  bay 
lies  a  conspicuous  bright  point,  the  crater  mountain  Pro- 
clus,  on  which  the  sun  has  fully  risen  in  the  fourth  day  of 
the  moon,  and  which  reflects  the  light  with  extraordinary 
liveliness.  Adjoining  Proclus  on  the  east  and  south  is  a 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         159 

curious,  lozenge-shaped  flat,  broken  with  short,  low  ridges, 
and  possessing  a  most  peculiar  light-brown  tint,  easily  dis- 
tinguished from  the  general  color  tone  of  the  lunar  land- 
scapes. It  would  be  interesting  to  know  what  was  passing 
in  the  mind  of  the  old  astronomer  who  named  this  singular 

O 

region  Palus  Somnii.  It  is  not  the  only  spot  on  the  moon 
which  has  been  called  a  "  marsh,"  and  to  which  an  unex- 
plained connection  with  dreams  has  been  ascribed. 

Nearly  on  the  same  meridian  with  Proclus,  at  a  distance 
of  about  a  hundred  miles  northward,  lies  a  fine  example  of 
a  ring  mountain,  rather  more  than  forty  miles  in  diameter, 
and  with  peak-tipped  walls  which  in  some  places  are 
13,000  feet  in  height,  as  measured  from  the  floor  within. 
This  is  Macrobius.  There  is  an  inconspicuous  central 
mountain  in  the  ring. 

North  of  the  Mare  Crisium,  and  northwest  of  Macro- 
bius, we  find  a  much  larger  mountain  ring,  oblong  in 
shape  and  nearly  eighty  miles  in  its  greatest  diameter. 
It  is  named  Cleomenes.  The  highest  point  on  its  wall  is 
about  10,000  feet  above  the  interior.  Near  the  northeast 
corner  of  the  wall  yawns  a  huge  and  very  deep  crater, 
Tralles,  while  at  the  northern  end  is  another  oblong 
crater  mountain  called  Burckhardt. 

From  Cleomenes  northward  to  the  pole,  or  to  the 
northern  extremity  of  the  crescent,  if  our  observations 
are  made  during  new  moon,  the  ground  appears  broken 
with  an  immense  number  of  ridges,  craters,  and  mountain 
rings,  among  which  we  may  telescopically  wander  at  will. 
One  of  the  more  remarkable  of  these  objects,  which  may 
be  identified  with  the  aid  of  Lunar  Chart  No.  1,  is  the  vast 
ringed  plain  near  the  edge  of  the  disk,  named  Gauss.  It 
is  more  than  a  hundred  and  ten  miles  in  diameter.  Owing 
to  its  situation,  so  far  down  the  side  of  the  lunar  globe,  it 
is  foreshortened  into  a  long  ellipse,  although  in  reality  it 


160  PLEASURES  OF  THE  TELESCOPE 

is  nearly  a  circle.  A  chain  of  mountains  runs  north  and 
south  across  the  interior  plain.  Geminus,  Berzelius,  and 
Messala  are  other  rings  well  worth  looking  at.  The  re- 
markable pair  called  Atlas  and  Hercules  demand  more 
than  passing  attention.  The  former  is  fifty-five  and  the  lat- 
ter forty-six  miles  in  diameter.  Each  sinks  11,000  feet  be- 
low the  summit  of  the  loftiest  peak  on  its  encircling  wall. 
Both  are  full  of  interesting  detail  sufficient  to  occupy  the 
careful  observer  for  many  nights.  The  broad  ring  bearing 
the  name  of  Endymion  is  nearly  eighty  miles  in  diameter, 
and  has  one  peak  15,000  feet  high.  The  interior  plain  is  flat 
and  dark.  Beyond  Endymion  on  the  edge  of  the  disk  is 
part  of  a  gloomy  plain  called  the  Mare  Humboltianum. 

After  glancing  at  the  crater-shaped  mountains  on  the 
western  and  southern  border  of  the  Mare  Crisium,  Alha- 
zen,  Hansen,  Condorcet,  Firmicus,  etc.,  we  pass  southward 
into  the  area  covered  in  Lunar  Chart  No.  2.  The  long 
dark  plain  south  of  the  Mare  Crisium  is  the  Mare  Fecundi- 
tatiSy  though  why  it  should  have  been  supposed  to  be  par- 
ticularly fecund,  or  fertile,  is  by  no  means  clear.  On  the 
western  border  of  this  plain,  about  three  hundred  miles 
from  the  southern  end  of  the  Mare  Crisium,  is  the  mountain 
ring,  or  circumvallation,  called  Langrenus,  about  ninety 
miles  across  and  in  places  10,000  feet  high.  There  is  a  fine 
central  mountain  with  a  number  of  peaks.  Nearly  a  hun- 
dred miles  farther  south,  on  the  same  meridian,  lies  an 
equally  extensive  mountain  ring  named  Vendelinus.  The 
broken  and  complicated  appearance  of  its  northern  walls 
will  command  the  observer's  attention.  Another  similar 
step  southward,  and  still  on  the  same  meridian  brings  us  to 
a  yet  finer  mountain  ring,  slightly  larger  than  the  others, 
and  still  more  complicated  in  its  walls,  peaks,  and  terraces, 
and  in  its  surroundings  of  craters,  gorges,  and  broken 
ridges.  This  is  Petavius.  West  of  Petavius,  on  the  very 


THE  MOUNTAINS  AND  PLAINS   OF  THE  MOON 


161 


edge  of  the  disk,  is  a  wonderful  formation,  a  walled  plain 
named  Humboldt,  which  is  looked  down  upon  at  one  point 
near  its  eastern  edge  by  a  peak  16,000  feet  in  height. 
About  a  hundred  and  forty  miles  south  of  Petavius  is  the 


4&* 


LUNAK  CHART  No.  2,  SOUTHWEST  QUARTER. 

fourth  great  mountain  ring  lying  on  the  same  meridian. 
Its  name  is  Furnerius.  Look  particularly  at  the  brilliantly 
shining  crater  on  the  northeast  slope  of  the  outer  wall  of 
Furnerius. 


162  PLEASURES   OF  THE  TELESCOPE 

Suppose  that  our  observations  are  now  interrupted, 
to  be  resumed  when  the  moon,  about  "  seven  days  old,"  is 
in  its  first  quarter.  If  we  had  time,  it  would  be  a  most 
interesting  thing  to  watch  the  advance  of  the  lunar  sun- 
rise every  night,  for  new  beauties  are  displayed  almost 
from  hour  to  hour;  but,  for  the  purposes  of  our  descrip- 
tion, it  is  necessary  to  curtail  the  observations.  At  first 
quarter  one  half  of  the  lunar  hemisphere  which  faces  the 
earth  is  illuminated  by  the  sun,  and  the  line  of  sunrise 
runs  across  some  of  the  most  wonderful  regions  of  the 
moon. 

We  begin,  referring  once  more  to  Lunar  Chart  No.  1, 
in  the  neighborhood  of  the  north  pole  of  the  moon.  Here 
the  line  along  which  day  and  night  meet  is  twisted  and 
broken,  owing  to  the  roughness  of  the  lunar  surface. 
About  fifteen  degrees  southwest  of  the  pole  lies  a  remark- 
able square-cornered,  mountain-bordered  plain,  about 
forty  miles  in  length,  called  Barrow.  Very  close  to  the 
pole  is  a  ring  mountain,  about  twenty-five  miles  in  diam- 
eter, whose  two  loftiest  peaks,  8,000  to  9,000  feet  high, 
according  to  Neison,  must,  from  their  situation,  enjoy  per- 
petual day. 

The  long,  narrow,  dark  plain,  whose  nearest  edge  is 
about  thirty  degrees  south  of  the  pole,  is  the  Mare  Frigoris, 
bordered  on  both  sides  by  uplands  and  mountains.  At  its 
southern  edge  we  find  the  magnificent  Aristoteles,  a 
mountain  ring,  sixty  miles  across,  whose  immense  wall  is 
composed  of  terraces  and  ridges  running  up  to  lofty  peaks, 
which  rise  nearly  11,000  feet  above  the  floor  of  the  val- 
ley. About  a  hundred  miles  south  of  Aristoteles  is  Eudox- 
us,  another  fine  mountain  ring,  forty  miles  in  diameter, 
and  quite  as  deep  as  its  northern  neighbor.  These  two 
make  a  most  striking  spectacle. 

We  are  now  in  the  neighborhood  of  the  greatest  moun- 


THE  MOUNTAINS  AND  PLAINS  OF  TEE  MOON         163 

tain  chains  on  the  moon,  the  lunar  Alps  lying  to  the 
east  and  the  lunar  Caucasus  to  the  south  of  Aristoteles 
and  Eudoxus,  while  still  farther  south,  separated  from  the 
Caucasus  by  a  strait  not  more  than  a  hundred  miles 
broad,  begins  the  mighty  range  of  the  lunar  Apennines. 
We  first  turn  the  telescope  on  the  Alps.  As  the  line  of 
sunrise  runs  directly  across  their  highest  peaks,  the  effect 
is  startling.  The  greatest  elevations  are  about  12,000 
feet.  The  observer's  eye  is  instantly  caught  by  a  great 
valley,  running  like  a  furrow  through  the  center  of  the 
mountain  mass,  and  about  eighty  or  ninety  miles  in 
length.  The  sealike  expanse  south  and  southeast  of  the 
Alps  is  the  Mare  Imbrium,  and  it  is  along  the  coast  of  this 
so-called  sea  that  the  Alps  attain  their  greatest  height. 
The  valley,  or  gorge,  above  mentioned,  appears  to  cut 
through  the  loftiest  mountains  and  to  reach  the  "  coast," 
although  it  is  so  narrowed  and  broken  among  the  greater 
peaks  that  its  southern  portion  is  almost  lost  before  it 
actually  reaches  the  Mare  Imbrium.  Opening  wider  again 
as  it  enters  the  Mare,  it  forms  a  deep  bay  among  precipi- 
tous mountains. 

The  Caucasus  Mountains  are  not  so  lofty  nor  so  pre- 
cipitous as  the  Alps,  and  consequently  have  less  attrac- 
tion for  the  observer.  They  border  the  dark,  oval  plain  of 
the  Mare  Serenitatis  on  its  northeastern  side.  The  great 
bay  running  out  from  the  Mare  toward  the  northwest,  be- 
tween the  Caucasus  and  the  huge  mountain  ring  of  Posi- 
donius,  bears  the  fanciful  name  of  Lacus  Somniorum.  In 
the  old  days  when  the  moon  was  supposed  to  be  inhabited, 
those  terrestrial  godfathers,  led  by  the  astronomer  Ricci- 
oli,  who  were  busy  bestowing  names  upon  the  "  seas  "  and 
mountains  of  our  patient  satellite,  may  have  pleased  their 
imagination  by  picturing  this  arm  of  the  "  Serene  Sea  "  as 
a  peculiarly  romantic  sheet  of  water,  amid  whose  magni- 


164  PLEASURES  OF  THE  TELESCOPE 

cal  influences  the  lunar  gentlefolk,  drifting  softly  in  their 
silver  galleons  and  barges,  and  enjoying  the  splendors  of 
"  full  earth  "  poured  upon  their  delightful  little  world, 
were  accustomed  to  fall  into  charming  reveries,  as  even 
we  hard-headed  sons  of  Adam  occasionally  do  when  the 
waters  under  the  keel  are  calm  and  smooth  and  the  balmy 
air  of  a  moonlit  night  invokes  the  twin  spirits  of  poetry 
and  music. 

Posidonius,  the  dominating  feature  of  the  shore  line 
here,  is  an  extraordinary  example  of  the  many  formations 
on  the  moon  which  are  so  different  from  everything  on 
the  earth  that  astronomers  do  not  find  it  easy  to  bestow 
upon  them  names  that  truly  describe  them.  It  may  be 
called  a  ring  mountain  or  a  ringed  plain,  for  it  is  both. 
Its  diameter  exceeds  sixty  miles,  and  the  interior  plain 
lies  about  2,000  feet  below  the  outer  surface  of  the  lunar 
ground.  The  mountain  wall  surrounding  the  ring  is  by 
no  means  remarkable  for  elevation,  its  greatest  height 
not  exceeding  6,000  feet,  but,  owing  to  the  broad  sweep  of 
the  curved  walls,  the  brightness  of  the  plain  they  inclose, 
and  the  picturesque  irregularity  of  the  silhouette  of 
shadow  thrown  upon  the  valley  floor  by  the  peaks  encir- 
cling it,  the  effect  produced  upon  the  observer  is  very 
striking  and  attractive. 

Having  finished  with  Posidonius  and  glanced  across 
the  broken  region  of  the  Taurus  Mountains  toward  the 
west,  we  turn  next  to  consider  the  Mare  Serenitatis.  This 
broad  gray  plain,  which,  with  a  slight  magnifying  power, 
certainly  looks  enough  like  a  sea  to  justify  the  first  tele- 
scopists  in  thinking  that  it  might  contain  water,  is  about 
430  by  425  miles  in  extent,  its  area  being  125,000  square 
miles.  Running  directly  through  its  middle,  nearly  in  a 
north  and  south  line,  is  a  light  streak,  which  even  a  good 
opera  glass  shows.  This  streak  is  the  largest  and  most 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON        165 

wonderful  of  the  many  similar  rays  which  extend  on  all 
sides  from  the  great  crater,  or  ring,  of  Tycho  in  the  south- 
ern hemisphere.  The  ray  in  question  is  more  than  2,000 
miles  long,  and,  like  its  shorter  congeners,  it  turns  aside 
for  nothing;  neither  "  sea,"  nor  peak,  nor  mountain  range, 
nor  crater  ring,  nor  gorge,  nor  caiion,  is  able  to  divert  it 
from  its  course.  It  ascends  all  heights  and  drops  into 
all  depths  with  perfect  indifference,  but  its  continuity  is 
not  broken.  When  the  sun  does  not  illuminate  it  at  a 
proper  angle,  however,  the  mysterious  ray  vanishes.  Is 
it  a  metallic  vein,  or  is  it  volcanic  lava  or  ash?  Was  the 
globe  of  the  moon  once  split  open  along  this  line? 

The  Mare  Serenitatis  is  encircled  by  mountain  ranges  to 
a  greater  extent  than  any  of  the  other  lunar  "  seas."  On 
its  eastern  side  the  Caucasus  and  the  Apennines  shut  it  in, 
except  for  a  strait  a  hundred  miles  broad,  by  means  of 
which  it  is  connected  with  the  Mare  Imbrium.  On  the 
south  the  range  of  the  Hsemus  Mountains  borders  it,  on 
the  north  and  northwest  the  Caucasus  and  the  Taurus 
Mountains  confine  it,  while  on  the  west,  where  again  it 
connects  itself  by  a  narrow  strait  with  another  "  sea," 
the  Mare  TranquiUtatis,  it  encounters  the  massive  uplift 
of  Mount  Argseus.  Not  far  from  the  eastern  strait  is 
found  the  remarkable  little  crater  named  Linne',  not  con- 
spicuous on  the  gray  floor  of  the  Mare,  yet  easily  enough 
found,  and  very  interesting  because  a  considerable  change 
of  form  seems  to  have  come  over  this  crater  some  time 
near  the  middle  of  the  nineteenth  century.  In  referring 
to  it  as  a  crater  it  must  not  be  forgotten  that  it  does 
not  form  an  opening  in  the  top  of  a  mountain.  In  fact, 
the  so-called  craters  on  the  moon,  generally  speaking,  are 
simply  cavities  in  the  lunar  surface,  whose  bottoms  lie 
deep  below  the  general  level,  instead  of  being  elevated  on 
the  summit  of  mountains,  and  inclosed  in  a  conical  peak. 


166  PLEASURES  OF  THE  TELESCOPE 

In  regard  to  the  alleged  change  in  Linne,  it  has  been  sug- 
gested, not  that  a  volcanic  eruption  brought  it  about,  but 
that  a  downfall  of  steep  walls,  or  of  an  unsupported  rocky 
floor,  was  the  cause.  The  possibility  of  such  an  occur- 
rence, it  must  be  admitted,  adds  to  the  interest  of  the  ob- 
server who  regularly  studies  the  moon  with  a  telescope. 

Just  on  the  southern  border  of  the  Mare,  the  beautiful 
ring  Menelaus  lies  in  the  center  of  the  chain  of  the  Hsemus 
Mountains.  The  ring  is  about  twenty  miles  across,  and 
its  central  peak  is  composed  of  some  highly  reflecting 
material,  so  that  it  shines  very  bright.  The  streak  or 
ray  from  Tycho  which  crosses  the  Mare  Serenitatis  passes 
through  the  walls  of  Menelaus,  and  perhaps  the  central 
peak  is  composed  of  the  same  substance  that  forms  the  ray. 
Something  more  than  a  hundred  miles  east-southeast 
from  Menelaus,  in  the  midst  of  the  dark  Mare  Vaporum,  is 
another  brilliant  ring  mountain  which  catches  the  eye, 
Manilius.  It  exceeds  Menelaus  in  brightness  as  well  as 
in  size,  its  diameter  being  about  twenty-five  miles.  There 
is  something  singular  underlying  the  dark  lunar  surface 
here,  for  not  only  is  Manilius  extraordinarily  brilliant  in 
contrast  with  the  surrounding  plain,  but  out  of  that  plain, 
about  forty  miles  toward  the  east,  projects  a  small  moun- 
tain which  is  also  remarkable  for  its  reflecting  properties, 
as  if  the  gray  ground  were  underlain  by  a  stratum  of  some 
material  that  flashes  back  the  sunlight  wherever  it  is  ex- 
posed. The  crater  mountain,  Sulpicius  Gallus,  on  the  bor- 
der of  the  Mare,  north  of  Manilius  and  east  of  Menelaus,  is 
another  example  of  the  strange  shining  quality  of  certain 
formations  on  the  moon. 

Follow  next  the  Ha3mus  range  westward  until  the  at- 
tention falls  upon  the  great  ring  mountain  Plinius,  more 
than  thirty  miles  across,  and  bearing  an  unusual  resem- 
blance to  a  fortification.  Mr.  T.  G.  Elger,  the  celebrated 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         167 

English  selenographer,  says  of  Plinius  that,  at  sunrise, 
"  it  reminds  one  of  a  great  fortress  or  redoubt  erected  to 
command  the  passage  between  the  Mare  Tranquilitatis  and 
the  Mare  Serenitatis."  But,  of  course,  the  resemblance  is 
purely  fanciful.  Men,  even  though  they  dwelt  in  the 
moon,  would  not  build  a  rampart  6,000  feet  high! 

Mount  Argseus,  at  the  southwest  corner  of  the  Mare 
Serenitatis,  is  a  very  wonderful  object  when  the  sun  has 
just  risen  upon  it.  This  occurs  five  days  after  the  new 
moon. 

Keturning  to  the  eastern  extremity  of  the  Mare,  we 
glance,  in  passing,  at  the  precipitous  Mount  Hadley,  which 
rises  more  than  15,000  feet  above  the  level  of  the  Mare  and 
forms  the  northern  point  of  the  Apennine  range.  Passing 
into  the  region  of  the  Mare  Imbrium,  whose  western  end  is 
divided  into  the  Palus  Putredinis  on  the  south  and  the 
Palus  Nebularum  on  the  north,  we  notice  three  conspicu- 
ous ring  mountains,  Cassini  near  the  Alps,  and  Aristillus 
and  Autolycus,  a  beautiful  pair,  nearly  opposite  the 
strait  connecting  the  two  Maria.  Cassini  is  thirty-six 
miles  in  diameter,  Aristillus  thirty-four,  and  Autolycus 
twenty-three.  The  first  named  is  shallow,  only  4,000  feet 
in  depth  from  the  highest  point  of  its  wall,  while  Aristil- 
lus carries  some  peaks  on  its  girdle  11,000  feet  high.  Au- 
tolycus, like  Cassini,  is  of  no  very  great  depth. 

Westward  from  the  middle  of  an  imaginary  line  joining 
Aristillus  and  Cassini  is  the  much  smaller  crater  Thesete- 
tus.  Outside  the  walls  of  this  are  a  number  of  craterlets, 
and  a  French  astronomer,  Charbonneaux,  of  the  Meudon 
Observatory,  reported  in  December,  1900,  that  he  had  re- 
peatedly observed  white  clouds  appearing  and  disappear- 
ing over  one  of  these  small  craters. 

South  of  the  Mare  Vaporum  are  found  some  of  the  most 
notable  of  those  strange  lunar  features  that  are  called 


168  PLEASURES  OF  THE  TELESCOPE 

"clefts  "  or  "  rills."  Two  crater  mountains,  in  particular, 
are  connected  with  them,  Ariadseus  at  the  eastern  edge  of 
the  Mare  Tranquilitatis  and  Hyginus  on  the  southern  bor- 
der of  the  Mare  Vaporum.  These  clefts  appear  to  be  broad 
and  deep  chasms,  like  the  caiions  cut  by  terrestrial  rivers, 
but  it  can  not  be  believed  that  the  lunar  canons  are  the 
work  of  rivers.  They  are  rather  cracks  in  the  lunar  crust, 
although  their  bottoms  are  frequently  visible.  The  prin- 
cipal cleft  from  Ariadseus  runs  eastward  and  passes  be- 
tween two  neighboring  craters,  the  southern  of  which  is 
named  Silberschlag,  and  is  noteworthy  for  its  brightness. 
The  Hyginus  cleft  is  broader  and  runs  directly  through 
the  crater  ring  of  that  name. 

The  observer  will  find  much  to  interest  him  in  the 
great,  irregular,  and  much-broken  mountain  ring  called 
Julius  Caesar,  as  well  as  in  the  ring  mountains,  Godin, 
Agrippa,  and  Triesnecker.  The  last  named,  besides  pre- 
senting magnificent  shadows  when  the  sunlight  falls 
aslant  upon  it,  is  the  center  of  a  complicated  system  of 
rills,  some  of  which  can  be  traced  with  our  five-inch  glass. 

We  next  take  up  Lunar  Chart  No.  2,  and  pay  a  tele- 
scopic visit  to  the  southwestern  quarter  of  the  lunar 
world.  The  Mare  Tranquilitatis  merges  through  straits 
into  two  southern  extensions,  the  More  Fecunditatis  and 
the  Mare  Ncctaris.  The  great  ring  mountains  or  ringed 
plains,  Langrenus,  Vendelinus,  Petavius,  and  Furnerius, 
all  lying  significantly  along  the  same  lunar  meridian,  have 
already  been  noticed.  Their  linear  arrangement  and  iso- 
lated position  recall  the  row  of  huge  volcanic  peaks  that 
runs  parallel  with  the  shore  of  the  Pacific  Ocean  in  Oregon 
and  Washington — Mount  Jefferson,  Mount  Hood,  Mount 
St.  Helen's,  Mount  Tacoma — but  these  terrestrial  volca- 
noes, except  in  elevation,  are  mere  pins'  heads  in  the  com- 
parison. 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         169 

In  the  eastern  part  of  the  Mare  Fecunditatis  lies  a  pair 
of  relatively  small  craters  named  Messier,  which  possess 
particular  interest  because  it  has  been  suspected,  though 
not  proved,  that  a  change  of  form  has  occurred  in  one  or 
other  of  the  pair.  Madler,  in  the  first  half  of  the  nine- 
teenth century,  represented  the  two  craters  as  exactly 
alike  in  all  respects.  In  1855  Webb  discovered  that  they 
are  not  alike  in  shape,  and  that  the  easternmost  one  is  the 
larger,  and  every  observer  easily  sees  that  Webb's  descrip- 
tion is  correct.  Messier  is  also  remarkable  for  the  light 
streak,  often  said  to  resemble  a  comet's  tail,  which  ex- 
tends from  the  larger  crater  eastward  to  the  shore  of  the 
Mare  Fecunditatis. 

Goclenius  and  Guttemberg,  on  the  highland  between 
the  Mare  Fecunditatis  and  the  Mare  Nectaris,  are  intersected 
and  surrounded  by  clefts,  besides  being  remarkable  for 
their  broken  and  irregular  though  lofty  walls.  Guttem- 
berg is  forty-five  miles  and  Goclenius  twenty-eight  miles 
in  diameter.  The  short  mountain  range  just  east  of  Gut- 
temberg, and  bordering  a  part  of  the  Mare  Nectaris  on  the 
west,  is  called  the  Pyrenees. 

The  Mare  Nectaris,  though  offering  in  its  appearance  no 
explanation  of  its  toothsome  name — perhaps  it  was  re- 
garded as  the  drinking  cup  of  the  Olympian  gods — is  one 
of  the  most  singular  of  the  dark  lunar  plains  in  its  out- 
lines. At  the  south  it  ends  in  a  vast  semicircular  bay, 
sixty  miles  across,  which  is  evidently  a  half-submerged 
mountain  ring.  But  submerged  by  what?  Not  water, 
but  perhaps  a  sea  of  lava  which  has  now  solidified  and 
forms  the  floor  of  the  M are  Nectaris.  The  name  of  this  sin- 
gular formation  is  Fracastorius.  Elger  has  an  interest- 
ing remark  about  it. 

"  On  the  higher  portion  of  the  interior,  near  the  cen- 
ter," he  says,  "  is  a  curious  object  consisting  apparently  of 
13 


170  PLEASURES  OF  THE  TELESCOPE 

four  light  spots,  arranged  in  a  square,  with  a  craterlet  in 
the  middle,  all  of  which  undergo  notable  changes  of  aspect 
under  different  phases." 

Other  writers  also  call  attention  to  the  fine  markings, 
minute  craterlets,  and  apparently  changeable  spots  on  the 
floor  of  Fracastorius. 

We  go  now  to  the  eastern  side  of  the  Mare  Nectaris, 
where  we  find  one  of  the  most  stupendous  formations  in 
the  lunar  world,  the  great  mountain  ring  of  Theophilus, 
noticeably  regular  in  outline  and  perfect  in  the  complete- 
ness of  its  lofty  wall.  The  circular  interior,  which  con- 
tains in  the  center  a  group  of  mountains,  one  of  whose 
peaks  is  6,000  feet  high,  sinks  10,000  feet  below  the  gen- 
eral level  of  the  moon  outside  the  wall!  One  of  the  peaks 
on  the  western  edge  towers  more  than  18,000  feet  above 
the  floor  within,  while  several  other  peaks  attain  eleva- 
tions of  15,000  to  16,000  feet.  The  diameter  of  the  immense 
ring,  from  crest  to  crest  of  the  wall,  is  sixty-four  miles. 
Theophilus  is  especially  wonderful  on  the  fifth  and  sixth 
days  of  the  moon,  when  the  sun  climbs  its  shining  pinna- 
cles and  slowly  discloses  the  tremendous  chasm  that  lies 
within  its  circles  of  terrible  precipices. 

On  the  southeast  Theophilus  is  connected  by  exten- 
sions of  its  walls  with  a  shattered  ring  of  vast  extent 
called  Cyrillus;  and  south  from  Cyrillus,  and  connected 
with  the  same  system  of  broken  walls,  lies  the  still  larger 
ring  named  Catharina,  whose  half-ruined  walls  and  numer- 
ous crater  pits  present  a  fascinating  spectacle  as  the 
shadows  retreat  before  the  sunrise  advancing  across 
them.  These  three — Theophilus,  Cyrillus,  and  Catharina 
—constitute  a  scene  of  surpassing  magnificence,  a  glimpse 
of  wonders  in  another  world  sufficient  to  satisfy  the  most 
riotous  imagination. 

South  of  the  Mare  Nectaris  the  huge  ring  mountain  of 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         171 

Piccolomini  attracts  attention,  its  massive  walls  sur- 
rounding a  floor  nearly  sixty  miles  across,  and  rising 
in  some  places  to  an  altitude  of  nearly  15,000  feet.  It 
should  be  understood  that  wherever  the  height  of  the 
mountain  wall  of  such  a  ring  is  mentioned,  the  refer- 
ence level  is  that  of  the  interior  plain  or  floor.  The 
elevation,  reckoned  from  the  outer  side,  is  always  very 
much  less. 

The  entire  region  south  and  east  of  Theophilus  and  its 
great  neighbors  is  marvelously  rough  and  broken.  Ap- 
proaching the  center  of  the  moon,  we  find  a  system  of 
ringed  plains  even  greater  in  area  than  any  of  those  we 
have  yet  seen.  Hipparchus  is  nearly  a  hundred  miles 
long  from  north  to  south,  and  nearly  ninety  miles  broad 
from  east  to  west.  But  its  walls  have  been  destroyed 
to  such  an  extent  that,  after  all,  it  yields  in  grandeur  to  a 
formation  like  Theophilus. 

Albategnius  is  sixty-five  miles  across,  with  peaks  from 
10,000  to  15,000  feet  in  height.  Sacrobosco  is  a  confused 
mass  of  broken  and  distorted  walls.  Aliacensis  is  re- 
markable for  having  a  peak  on  the  eastern  side  of  its  wall 
which  is  more  than  16,000  feet  high.  Werner,  forty-five 
miles  in  diameter,  is  interesting  because  under  its  north- 
eastern wall  Miidler,  some  seventy  years  ago,  saw  a  light 
spot  of  astonishing  brightness,  unmatched  in  that  respect 
by  anything  on  the  moon  except  the  peak  of  Aristarchus, 
which  we  shall  see  later.  This  spot  seems  afterward  to 
have  lost  brilliance,  and  the  startling  suggestion  has  been 
made  that  its  original  brightness  might  have  been  due  to 
its  then  recent  deposit  from  a  little  crater  that  lies  in  the 
midst  of  it.  Walter  is  of  gigantic  dimensions,  about  one 
hundred  miles  in  diameter.  Unlike  the  majority  of  the 
ringed  plains,  it  departs  widely  from  a  circle.  Stofler  is 
yet  larger  than  Walter;  but  most  interesting  of  all  these 


172  PLEASURES  OF  THE  TELESCOPE 

gigantic  formations  is  Maurolycus,  whose  diameter  ex- 
ceeds one  hundred  and  fifty  miles,  and  which  has  walls 
13,000  or  14,000  feet  high.  Yet,  astonishing  though  it 
may  seem,  this  vast  and  complicated  mass  of  mountain 
walls,  craters,  and  peaks,  is  virtually  unseen  at  full  moon, 
owing  to  the  perpendicularity  of  the  sunlight,  which  pre- 
vents the  casting  of  shadows. 

We  shall  next  suppose  that  another  period  of  about 
seven  days  has  elapsed,  the  moon  in  the  meantime  reach- 
ing its  full  phase.  We  refer  for  guidance  to  Lunar  Chart 
No.  3.  The  peculiarity  of  the  northeastern  quadrant 
which  immediately  strikes  the  eye  is  the  prevalence  of  the 
broad  plains  called  if  aria,  or  "  seas."  The  northern  and 
central  parts  are  occupied  by  the  Mare  Imbrium,  the  "  Sea 
of  Showers  "  or  of  "  Rains,"  with  its  darljp  bay  the  Sinus 
Mstuum,  while  the  eastern  half  is  covered  by  the  vast 
Oceanus  Procellarum,  the  "  Ocean  of  Storms  "  or  of  "  Tem- 
pests." 

Toward  the  north  a  conspicuous  oval,  remarkably  dark 
in  hue,  immediately  attracts  our  attention.  It  is  the  cele- 
brated ringed  plain  of  Plato,  about  sixty  miles  in  diameter 
and  surrounded  by  a  saw-edged  rampart,  some  of  whose 
pinnacles  are  6,000  or  7,000  feet  high.  Plato  is  a  favor- 
ite subject  for  study  by  selenographers  because  of  the 
changes  of  color  which  its  broad,  flat  floor  undergoes  as 
the  sun  rises  upon  it,  and  also  because  of  the  existence  of 
enigmatical  spots  and  streaks  whose  visibility  changes. 
South  of  Plato,  in  the  Mare  Imbrium,  rises  a  precipitous, 
isolated  peak  called  Pico,  8,000  feet  in  height.  Its  resem- 
blance in  situation  to  the  conical  mountain  Pico  in  the 
Azores  strikes  the  observer. 

Eastward  of  Plato  a  line  of  highlands,  separating  the 
Mare  Imbrium  from  the  Mare  Frigoris,  carries  the  eye  to 
the  beautiful  semicircular  Sinus  Iridum,  or  "  Bay  of  Rain- 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         173 


bows."  The  northwestern  extremity  of  this  remarkable 
bay  is  guarded  by  a  steep  and  lofty  promontory  called 
Cape  Laplace,  while  the  southeastern  extremity  also  has 
its  towering  guardian,  Cape  Heraclides.  The  latter  is 


MBDII 


<£$Gambart 


Encke 
9   W 

(,       \  / 

.  \\Kepter     \    f 


V 
Bevel        °( 


,      .SINUS      S-TUUM 


Galileo    Uhi 

* 


?     '    f/ 

i'/  / 


LUNAR  CHART  No.  3,  NORTHEAST  QUARTER. 


interesting  for  showing,  between  nine  and  ten  days  after 
full  moon,  a  singularly  perfect  profile  of  a  woman's  face 
looking  out  across  the  Mare  Tmbrium.  The  winding  lines, 
like  submerged  ridges,  delicately  marking  the  floor  of  the 
Sinus  Iridum  and  that  of  the  Mare  beyond,  are  beautiful 


174  PLEASURES  OF  THE  TELESCOPE 

telescopic  objects.  The  "  bay  "  is  about  one  hundred  and 
thirty-five  miles  long  by  eighty-four  broad. 

The  Mare  Imlrium,  covering  340,000  square  miles,  is 
sparingly  dotted  over  with  craters.  All  of  the  more  con- 
spicuous of  them  are  indicated  in  the  chart.  The  smaller 
ones,  like  Caroline  Herschel,  Helicon,  Leverrier,  Delisle, 
etc,  vary  from  eight  to  twelve  miles  in  diameter.  Lam- 
bert is  seventeen  miles  in  diameter,  and  Euler  nineteen, 
while  Timocharis  is  twenty-three  miles  broad  and  7,000 
feet  deep  below  its  walls,  which  rise  only  3,000  feet  above 
the  surface  of  the  Mare. 

Toward  the  eastern  border  of  the  sea,  south  of  the  Har- 
binger Mountains,  we  find  a  most  remarkable  object,  the 
mountain  ring,  or  crater  plain,  called  Aristarchus.  This 
ring  is  not  quite  thirty  miles  in  diameter,  but  there  is 
nothing  on  the  moon  that  can  compare  with  it  in  dazzling 
brilliance.  The  central  peak,  1,200  or  1,300  feet  high, 
gleams  like  a  mountain  of  crusted  snow,  or  as  if  it  were 
composed  of  a  mass  of  fresh-broken  white  metal,  or  of  com- 
pacted crystals.  Part  of  the  inner  slope  of  the  east  wall  is 
equally  brilliant.  In  fact,  so  much  light  is  poured  out  of 
the  circumvallation  that  the  eye  is  partially  blinded,  and 
unable  distinctly  to  see  the  details  of  the  interior.  No 
satisfactory  explanation  of  the  extraordinary  reflecting 
power  of  Aristarchus  has  ever  been  offered.  Its  neighbor 
toward  the  east,  Herodotus,  is  somewhat  smaller  and 
not  remarkably  bright,  but  it  derives  great  interest  from 
the  fact  that  out  of  a  breach  in  its  northern  wall  issues 
a  vast  cleft,  or  chasm,  which  winds  away  for  nearly  a 
hundred  miles  across  the  floor  of  the  Mare,  making  an 
abrupt  turn  when  it  reaches  the  foot  of  the  Harbinger 
Mountains. 

The  comparatively  small  crater,  Lichtenberg,  near  the 
northeastern  limb  of  the  moon,  is  interesting  because  Mad- 


THE  MOUNTAINS  AND  PLAINS   OF  THE  MOON         175 

ler  used  to  see  in  its  neighborhood  a  pale-red  tint  which 
has  not  been  noticed  since  his  day. 

Returning  to  the  western  side  of  the  quadrant  repre- 
sented in  Lunar  Chart  No.  3,  we  see  the  broad  and  beauti- 
fully regular  ringed  plain  of  Archimedes,  fifty  miles  in 
diameter  and  4,000  feet  deep. 

A  number  of  clefts  extend  between  the  mountainous 
neighborhood  of  Archimedes  and  the  feet  of  the  gigantic 
Apennine  Mountains  on  the  southwest.  The  little  double 
crater,  Beer,  between  Archimedes  and  Timocharis,  is  very 
bright. 

The  Apennines  extend  about  four  hundred  and  eighty 
miles  in  a  northwesterly  and  southeasterly  direction. 
One  of  their  peaks  near  the  southern  end  of  the  range, 
Mount  Huygens,  is  at  least  18,000  feet  high,  and  the  black 
silhouettes  of  their  sharp-pointed  shadows  thrown  upon 
the  smooth  floor  of  the  Mare  Imbrium  about  the  time  of 
first  quarter  present  a  spectacle  as  beautiful  as  it  is 
unique.  The  Apennines  end  at  the  southeast  in  the  ring 
mountain,  Eratosthenes,  thirty-eight  miles  across  and 
very  deep,  one  of  its  encircling  chain  of  peaks  rising 
16,000  feet  above  the  floor,  and  about  half  that  height 
above  the  level  of  the  Mare  Imbrium.  The  shadows  cast 
by  Eratosthenes  at  sunrise  ar£  magnificent. 

And  now  we  come  to  one  of  the  supreme  spectacles  of 
the  moon,  the  immense  ring  or  crater  mountain  Coperni- 
cus. This  is  generally  regarded  as  the  grandest  object 
that  the  telescope  reveals  on  the  earth's  satellite.  It  is 
about  fifty-six  miles  across,  and  its  interior  falls  to  a 
depth  of  8,000  feet  below  the  Mare  Imbrium.  Its  broad 
wall,  composed  of  circle  within  circle  of  ridges,  terraces, 
and  precipices,  rises  on  the  east  about  12,000  feet  above 
the  floor.  On  the  inner  side  the  slopes  are  very  steep,  cliff 
falling  below  cliff,  until  the  bottom  of  the  fearful  abyss  is 


176  PLEASURES  OF  THE  TELESCOPE 

attained.  To  descend  th'ose  precipices  and  reach  the  de- 
pressed floor  of  Copernicus  would  be  a  memorable  feat  for 
a  mountaineer.  In  the  center  of  the  floor  rises  a  compli- 
cated mountain  mass  about  2,400  'feet  high.  All  around 
Copernicus  the  surface  of  the  moon  is  dotted  with  count- 
less little  crater  pits,  and  splashed  with  whitish  streaks. 
Northward  lie  the  Carpathian  Mountains,  terminating  on 
the  east  in  Tobias  Mayer,  a  ring  mountain  more  than 
twenty  miles  across.  The  mountain  ring  Kepler,  which  is 
also  the  center  of  a  great  system  of  whitish  streaks  and 
splashes,  is  twenty-two  miles  in  diameter,  and  notably 
brilliant. 

Finally,  we  turn  to  the  southeastern  quadrant  of  the 
moon,  represented  in  Lunar  Chart  No.  4.  The  broad, 
dark  expanse  extending  from  the  north  is  the  Mare  Nubium 
on  the  west  and  the  Oceanus  Procellarum  on  the  east.  To- 
ward the  southeast  appears  the  notably  dark,  rounded 
area  of  the  Mare  Humorum  inclosed  by  highlands  and 
rings.  We  begin  with  the  range  of  vast  inclosures  run- 
ning southward  near  the  central  meridian,  and  starting 
with  Ptolemseus,  a  walled  plain  one  hundred  and  fifteen 
miles  in  its  greatest  diameter  and  covering  an  area  con- 
siderably exceeding  that  of  the  State  of  Massachusetts. 
Its  neighbor  toward  the  south,  Alphonsus,  is  eighty-three 
miles  across.  Next  comes  Arzachel,  more  than  sixty-five 
miles  in  diameter.  Thebit,  more  than  thirty  miles  across, 
is  very  deep.  East  of  Thebit  lies  the  celebrated  "  lunar 
railroad,"  a  straight,  isolated  wall  about  five  hundred  feet 
high  and  sixty-five  miles  long,  dividing  at  its  southern  end 
into  a  number  of  curious  branches,  forming  the  buttresses 
of  a  low  mountain.  Purbach  is  sixty  miles  broad,  and 
south  of  that  comes  a  wonderful  region  where  the  ring 
mountains  Hell,  Ball,  Lexell,  and  others,  more  or  less 
connected  with  walls,  inclose  an  area  even  larger  than 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         177 


Ptolemseus,  but  which,  not  being  so  distinctly  bordered  as 
some  of  the  other  inclosed  plains,  bears  no  distinctive 
name. 

The  next  conspicuous  object  toward  the  south  ranks 
with  Copernicus  among  the  grandest  of  all  lunar  phe- 


$0g&#wfofl_.^ 

\\Sr-,"  ^3vW/J»Vy// J  4S         ^" -7V' 


^fetfte^ 


ijiqrii/iije 

_  Viet  a 

r^s*-^^'  N^^°*» 

ytomontaniis  MARE  ^S 

HUMORUM  0 

^     .  BulUaMus    ^  M  EMv>ta(^ 

\^' N&llet          ''Q;  AyatharchMes         to  '^'/^       0 

^J^rz^-A^/ 

ra^lT^IM^  NUBJUM 

^m  •  ®Lassell 


Parry?: 


-' 


Damoiseau 
Flamsteed  iQ 


^Landsbetyj 


LUNAR  CHART  No.  4,  SOUTHEAST  QUARTER. 


nomena — the  ring,  or  crater,  Tycho.  It  is  about  fifty-four 
miles  in  diameter  and  some  points  on  its  wall  rise  17,000 
feet  above  the  interior.  In  the  center  is  a  bright  moun- 


178  PLEASURES  OF  THE  TELESCOPE 

tain  peak  5,000  feet  high.  But  wonderful  as  are  the  de- 
tails of  its  mountain  ring,  the  chief  attraction  of  Tycho  is 
its  manifest  relation  to  the,  mysterious  bright  rays  hereto- 
fore referred  to,  which  extend  far  across  the  surface  of 
the  moon  in  all  directions,  and  of  which  it  is  the  center. 
The  streaks  about  Copernicus  are  short  and  confused,  con- 
stituting rather  a  splash  than  a  regular  system  of  rays; 
but  those  emanating  from  Tycho  are  very  long,  regular, 
comparatively  narrow,  and  form  arcs  of  great  circles  which 
stretch  away  for  hundreds  of  miles,  allowing  no  obstacle  to 
interrupt  their  course. 

Southwest  of  Tycho  lies  the  vast  ringed  plain  of  Ma- 
ginus,  a  hundred  miles  broad  and  very  wonderful  to  look 
upon,  with  its  labyrinth  of  formations,  when  the  sun 
slopes  across  it,  and  yet,  like  Maurolycus,  invisible  under 
a  vertical  illumination.  "  The  full  moon,"  to  use  Mad- 
ler's  picturesque  expression,  "  knows  no  Maginus."  Still 
larger  and  yet  more  splendid  is  Clavius,  which  exceeds 
.one  hundred  and  forty  miles  in  diameter  and  covers  16,000 
square  miles  of  ground  within  its  fringing  walls,  which 
carry  some  of  the  loftiest  peaks  on  the  moon,  several  at- 
taining 17,000  feet.  The  floor  is  deeply  depressed,  so  that 
an  inhabitant  of  this  singular  inclosure,  larger  than  Massa- 
chusetts, Connecticut,  and  Rhode  Island  combined,  would 
dwell  in  land  sunk  two  miles  below  the  general  level  of 
the  world  about  him. 

In  the  neighborhood  of  the  south  pole  lies  the  large 
walled  plain  of  Newton,  whose  interior  is  the  deepest 
known  depression  on  the  moon.  It  is  so  deep  that  the  sun- 
shine never  touches  the  larger  part  of  the  floor  of  the 
inner  abyss,  and  a  peak  on  its  eastern  wall  rises  24,000 
feet  sheer  above  the  tremendous  pit.  Other  enormous 
walled  plains  are  Longomontanus,  Wilhelm  I,  Schiller, 
Bailly,  and  Schickard.  The  latter  is  one  hundred  and 


THE  MOUNTAINS  AND  PLAINS  OF  THE  MOON         179 

thirty-four  miles  long  and  bordered  by  a  ring  varying  from 
4,000  to  9,000  feet  in  height.  Wargentin,  the  oval  close  to 
the  moon's  southeast  limb,  beyond  Schickard,  is  a  unique 
formation  in  that,  instead  of  its  interior  being  sunk  be- 
low the  general  level,  it  is  elevated  above  it.  It  has  been 
suggested  that  this  peculiarity  is  due  to  the  fact  that  the 
floor  of  Wargentin  was  formed  by  inflation  from  below, 
and  that  it  has  cooled  and  solidified  in  the  shape  of  a 
gigantic  dome  arched  over  an  immense  cavity  beneath.  A 
dome  of  such  dimensions,  however,  could  not  retain  its 
form  unless  partly  supported  from  beneath. 

Hainzel  is  interesting  from  its  curious  outline;  Cichus 
for  the  huge  yawning  crater  on  its  eastern  wall;  Capu- 
anus  for  a  brilliant  shining  crater  also  on  its  eastern  wall; 
and  Mercator  for  possessing  bright  craters  on  both  its 
east  and  its  west  walls.  Vitello  has  a  bright  central 
mountain  and  gains  conspicuousness  from  its  position  at 
the  edge  of  the  dark  Mare  Humorum.  Agatharchides  is 
the  broken  remnant  of  a  great  ring  mountain.  Gassendi, 
an  extremely  beautiful  object,  is  about  fifty-five  miles 
across.  It  is  encircled  with  broken  walls,  craters  and 
and  bright  points,  and  altogether  presents  a 'very  splen- 
did appearance  about  the  eleventh  day  of  the  moon's  age. 

Letronne  is  a  half-submerged  ring,  at  the  southern  end 
of  the  Oceanus  Procellarum,  which  recalls  Fracastorius  in 
the  western  lunar  hemisphere.  It  lies,  however,  ten  de- 
grees nearer  the  equator  than  Fracastorius.  Billy  is  a 
mountain  ring  whose  interior  seems  to  have  been  sub- 
merged by  the  dark  substance  of  the  Oceanus  Procellarum, 
although  its  walls  have  remained  intact.  Mersenius  is  a 
very  conspicuous  ring,  forty  miles  in  diameter,  east  of  the 
Mare  Humorum.  Vieta,  fifty  miles  across,  is  also  a  fine 
object.  Grimaldi,  a  huge  dusky  oval,  is  nearly  one  hun- 
dred and  fifty  miles  in  its  greatest  length.  The  ring  moun- 


180  PLEASURES  OF  THE  TELESCOPE 

tain  Landsberg,  on  the  equator,  and  near  the  center  of 
the  visible  eastern  hemisphere,  is  worth  watching  because 
Elger  noticed  changes  of  color  in  its  interior  in  1888. 

Bullialdus,  in  the  midst  of  the  Mare  Nubium,  is  a  very 
conspicuous  and  beautiful  ring  mountain  about  thirty- 
eight  miles  in  diameter,  with  walls  8,000  feet  high  above 
the  interior. 

Those  who  wish  to  see  the  lunar  mountains  in  all  their 
varying  aspects  will  not  content  themselves  with  views 
obtained  during  the  advance  of  the  sunlight  from  west  to 
east,  between  "  new  moon  "  and  "  full  moon,"  but  will  con- 
tinue their  observations  during  the  retreat  of  the  sunlight 
from  east  to  west,  after  the  full  phase  is  passed. 

It  is  evident  that  the  hemisphere  of  the  moon  which  is 
forever  turned  away  from  the  earth  is  quite  as  marvelous 
in  its  features  as  the  part  that  we  see.  It  will  be  noticed 
that  the  entire  circle  of  the  moon's  limb,  with  insignificant 
interruptions,  is  mountainous.  Possibly  the  invisible  side 
of  our  satellite  contains  yet  grander  peaks  and  crater 
mountains  than  any  that  our  telescopes  can  reach.  This 
probability  is  increased  by  the  fact  that  the  loftiest 
known  mountain  on  the  moon  is  neyer  seen  except  in  sil- 
houette. It  is  a  member  of  a  great  chain  that  breaks  the 
lunar  limb  west  of  the  south  pole,  and  that  is  called  the 
Leibnitz  Mountains.  The  particular  peak  referred  to  is 
said  by  some  authorities  to  exceed  30,000  feet  in  height. 
Other  great  ranges  seen  only  in  profile  are  the  Dorfel 
Mountains  on  the  limb  behind  the  ring  plain  Bailly,  the 
Cordilleras,  east  of  Eichstadt,  and  the  D'Alembert  Moun- 
tains beyond  Grimaldi.  The  profile  of  these  great  moun- 
tains is  particularly  fine  when  they  are  seen  during  an 
eclipse  of  the  sun.  Then,  with  the  disk  of  the  sun  for  a 
background,  they  stand  out  with  startling  distinctness. 


TEE  SPECTACLES  OF  THE  SUN  181 

THE  SUN 

When  the  sun  is  covered  with  spots  it  becomes  a  most 
interesting  object  for  telescopic  study.  Every  amateur's 
telescope  should  be  provided  with  apparatus  for  viewing 
the  sun.  A  dark  shade  glass  is  not  sufficient  and  not  safe. 
What  is  known  as  a  solar  prism,  consisting  of  two  solid 
prisms  of  glass,  cemented  together  in  a  brass  box  which 
carries  a  short  tube  for  the  eyepiece,  and  reflecting  an  im- 
age of  the  sun  from  their  plane  of  junction — while  the 
major  remnant  of  light  and  heat  passes  directly  through 
them  and  escapes  from  an  opening  provided  for  the  pur- 
pose— serves  very  well.  Better  and  more  costly  is  an  ap- 
paratus called  a  helioscope,  constructed  on  the  principle 
of  polarization  and  provided  with  prisms  and  reflectors 
which  enable  the  observer,  by  proper  adjustment,  to  gov- 
ern very  exactly  and  delicately  the  amount  of  light  that 
passes  into  the  eyepiece. 

Furnished  with  an  apparatus  of  this  description  we 
can  employ  either  a  three-,  four-,  or  five-inch  glass  upon  the 
sun  with  much  satisfaction.  For  the  amateur's  purposes 
the  sun  is  only  specially  interesting  when  it  is  spotted. 
The  first  years  of  the  twentieth  century  will  behold  a 
gradual  growth  in  the  number  and  size  of  the  solar  spots 
as  those  years  happen  to  coincide  with  the  increasing 
phase  of  the  sun-spot  period.  Large  sun  spots  and  groups 
of  spots  often  present  an  immense  amount  of  detail  which 
tasks  the  skill  of  the  draughtsman  to  represent  it.  But  a 
little  practice  will  enable  one  to  produce  very  good  repre- 
sentations of  sun  spots,  as  well  as  of  the  whitish  patches 
called  faculse  by  which  they  are  frequently  surrounded. 

For  the  simple  purpose  of  exhibiting  the  spotted  face 
of  the  sun  without  much  magnifying  power,  a  telescope 
may  be  used  to  project  the  solar  image  on  a  white  sheet  or 


182  PLEASURES  OF  THE  TELESCOPE 

screen.  If  the  experiment  is  tried  in  a  room,  a  little  in- 
genuity will  enable  the  observer  to  arrange  a  curtain  cov- 
ering the  window  used,  in  such  a  way  as  to  exclude  all 
the  light  except  that  which  comes"  through  the  telescope. 
Then,  by  placing  a  sheet  of  paper  or  a  drawing  board  be- 
fore the  eyepiece  and  focusing  the  image  of  the  sun  upon 
it,  very  good  results  may  be  obtained. 

If  one  has  a  permanent  mounting  and  a  driving  clock, 
a  small  spectroscope  may  be  attached,  for  solar  observa- 
tions, even  to  a  telescope  of  only  four  or  five  inches  aper- 
ture, and  with  its  aid  most  interesting  views  may  be  ob- 
tained of  the  wonderful  red  hydrogen  flames  that  fre- 
quently appear  at  the  edge  of  the  solar  disk. 


CHAPTER    X 

ARE   THERE    PLANETS   AMONG   THE    STARS? 

"...  And  if  there  should  be 
Worlds  greater  than  thine  own,  inhabited 
By  greater  things,  and  they  themselves  far  more 
In  number  than  the  dust  of  thy  dull  earth, 
What  wouldst  thou  think  ?  " — BYRON'S  CAIN. 

THIS  always  interesting  question  has  lately  been  re- 
vived in  a  startling  manner  by  discoveries  that  have 
seemed  to  reach  almost  deep  enough  to  touch  its  solution. 
The  following  sentences,  from  the  pen  of  Dr.  T.  J.  J.  See, 
of  the  Lowell  Observatory,  are  very  significant  from  this 
point  of  view: 

"  Our  observations  during  1896-?97  have  certainly  dis- 
closed stars  more  difficult  than  any  which  astronomers 
had  seen  before.  Among  these  obscure  objects  about  half 
a  dozen  are  truly  wonderful,  in  that  they  seem  to  be  dark, 
almost  black  in  color,  and  apparently  are  shining  by  a  dull 
reflected  light.  It  is  unlikely  that  they  will  prove  to  be 
self-luminous.  If  they  should  turn  out  dark  bodies  in 
fact,  shining  only  by  the  reflected  light  of  the  stars  around 
which  they  revolve,  we  should  have  the  first  case  of 
planets — dark  bodies — noticed  among  the  fixed  stars." 

Of  course,  Dr.  See  has  no  reference  in  this  state- 
ment to  the  immense  dark  bodies  which,  in  recent  years, 
have  been  discovered  by  spectroscopic  methods  revolving 
around  some  of  the  visible  stars,  although  invisible  them- 
selves. The  obscure  objects  that  he  describes  belong  to 
a  different  class,  and  might  be  likened,  except  perhaps 

183 


184  PLEASURES  OF  THE  TELESCOPE 

in  magnitude,  to  the  companion  of  Sirius,  which,  though  a 
light-giving  body,  exhibits  nevertheless  a  singular  defect 
of  luminosity  in  relation  to  its  mass.  Sirius  has  only 
twice  the  mass,  but  ten  thousand-times  the  luminosity,  of 
its  strange  companion!  Yet  the  latter  is  evidently  rather 
a  faint,  or  partially  extinguished,  sun  than  an  opaque 
body  shining  only  with  light  borrowed  from  its  dazzling 
neighbor.  The  objects  seen  by  Dr.  See,  on  the  contrary, 
are  "  apparently  shining  by  a  dull  reflected  light." 

If,  however  (as  he  evidently  thinks  is  probable),  these 
objects  should  prove  to  be  really  non-luminous,  it  would 
not  follow  that  they  are  to  be  regarded  as  more  like  the 
planets  of  the  solar  system  than  like  the  dark  companions 
of  certain  other  stars.  A  planet,  in  the  sense  which  we 
attach  to  the  word,  can  not  be  comparable  in  mass  and 
size  with  the  sun  around  which  it  revolves.  The  sun  is  a 
thousand  times  larger  than  the  greatest  of  its  attendant 
planets,  Jupiter,  and  more  than  a  million  times  larger 
than  the  earth.  It  is  extremely  doubtful  whether  the  re- 
lation of  sun  and  planet  could  exist  between  two  bodies 
of  anything  like  equal  size,  or  even  if  one  exceeded  the 
other  many  times  in  magnitude.  It  is  only  when  the  dif- 
ference is  so  great  that  the  smaller  of  the  two  bodies  is 
insignificant  in  comparison  with  the  larger,  that  the  for- 
mer could  become  a  cool,  life-bearing  globe,  nourished  by 
the  beneficent  rays  of  its  organic  comrade  and  master. 

Judged  by  our  terrestrial  experience,  which  is  all  we 
have  to  go  by,  the  magnitude  of  a  planet,  if  it  is  to  bear 
life  resembling  that  of  the  earth,  is  limited  by  other  con- 
siderations. Even  Jupiter,  which,  as  far  as  our  knowl- 
edge extends,  represents  the  extreme  limit  of  great  plan- 
etary size,  may  be  too  large  ever  to  become  the  abode  of 
living  beings  of  a  high  organization.  The  force  of  gravi- 
tation on  the  surface  of  Jupiter  exceeds  that  on  the 


ARE  THERE  PLANETS  AMONG   THE  STARS?  185 

earth's  surface  as  2.64  to  1.  Considering  the  effects  of 
this  on  the  weight  and  motion  of  bodies,  the  density  of  the 
atmosphere,  etc.,  it  is  evident  that  Jupiter  would,  to  say 
the  very  least,  be  an  exceedingly  uncomfortable  place  of 
abode  for  beings  resembling  ourselves.  But  Jupiter,  if 
it  is  ever  to  become  a  solid,  rocky  globe  like  ours,  must 
shrink  enormously  in  volume,  since  its  density  is  only  0.24 
as  compared  with  the  earth.  Now,  the  surface  gravity  of 
a  planet  depends  on  its  mass  and  its  radius,  being  directly 
as  the  former  and  inversely  as  the  square  of  the  latter. 
But  in  shrinking  Jupiter  will  lose  none  of  its  mass,  al- 
though its  radius  will  become  much  smaller.  The  force  of 
gravity  will  consequently  increase  on  its  surface  as  the 
planet  gets  smaller  and  more  dense. 

The  present  mean  diameter  of  Jupiter  is  86,500  miles, 
while  its  mass  exceeds  that  of  the  earth  in  the  ratio  of  316 
to  1.  Suppose  Jupiter  shrunk  to  three  quarters  of  its 
present  diameter,  or  64,800  miles,  then  its  surface  gravity 
would  exceed  the  earth's  nearly  five  times.  With  one  half 
its  present  diameter  the  surface  gravity  would  become 
more  than  ten  times  that  of  the  earth.  On  such  a  planet 
a  man's  bones  would  snap  beneath  his  weight,  even  grant- 
ing that  he  could  remain  upright  at  all!  It  would  seem, 
then,  that,  unless  we  are  to  abandon  terrestrial  analogies 
altogether  and  "  go  it  blind,"  we  must  set  an  upper  limit 
to  the  magnitude  of  a  habitable  planet,  and  that  Jupiter 
represents  such  upper  limit,  if,  indeed,  he  does  not  tran- 
scend it. 

The  question  then  becomes,  Can  the  faint  objects  seen 
by  Dr.  See  and  his  fellow-observers,  in  the  near  neighbor- 
hood of  certain  stars,  be  planets  in  the  sense  just  de- 
scribed, or  are  they  necessarily  far  greater  in  magnitude 
than  the  largest  planet,  in  the  accepted  sense  of  that  word, 
which  can  be  admitted  into  the  category — viz.,  the  planet 

13 


186  PLEASURES  OF  THE  TELESCOPE 

Jupiter?  This  resolves  itself  into  another  question:  At 
what  distance  would  Jupiter  be  visible  with  a  powerful 
telescope,  supposing  it  to  receive  from  a  neighboring  star 
an  amount  of  illumination  not  les£  than  that  which  it  gets 
from  the  sun?  To  be  sure,  we  do  not  know  how  far  away 
the  faint  objects  described  by  Dr.  See  are;  but,  at  any  rate, 
we  can  safely  assume  that  they  are  at  the  distance  of 
the  nearest  stars,  say  somewhere  about  three  hundred 
thousand  times  the  earth's  distance  from  the  sun.  The 
sun  itself  removed  to  that  distance  would  appear  to  our 
only  as  a  star  of  the  first  magnitude.  But  Zollner 
shown  that  the  sun  exceeds  Jupiter  in  brilliancy 
5,472,000,000  times.  Seen  from  equal  distances,  however, 
the  ratio  would  be  about  218,000,000  to  1.  This  would  be 
the  ratio  of  their  light  if  both  sun  and  Jupiter  could  be 
removed  to  about  the  distance  of  the  nearest  stars.  Since 
the  sun  would  then  be  only  as  bright  as  one  of  the 
stars  of  the  first  magnitude,  and  since  Jupiter  would  be 
218,000,000  times  less  brilliant,  it  is  evident  that  the  latter 
would  not  be  visible  at  all.  The  faintest  stars  that  the 
most  powerful  telescopes  are  able  to  show  probably  do 
not  fall  below  the  sixteenth  or,  at  the  most,  the  seven- 
teenth magnitude.  But  a  seventeenth-magnitude  star  i& 
only  between  two  and  three  million  times  fainter  than  the 
sun  would  appear  at  the  distance  above  supposed,  while, 
as  we  have  seen,  Jupiter  would  be  more  than  two  hundred 
million  times  fainter  than  the  sun. 

To  put  it  in  another  way:  Jupiter,  at  the  distance  of 
the  nearest  stars,  would  be  not  far  from  one  hundred 
times  less  bright  than  the  faintest  star  which  the  largest 
telescope  is  just  able,  under  the  most  exquisite  conditions, 
to  glimpse.  To  see  a  star  so  faint  as  that  would  require 
an  object-glass  of  a  diameter  half  as  great  as  the  length 
of  the  tube  of  the  Lick  telescope,  or  say  thirty  feet! 


ARE  THERE  PLANETS  AMONG   THE  STARS f  187 

Of  course,  Jupiter  might  be  more  brilliantly  illumi- 
nated by  a  brighter  star  than  the  sun;  but,  granting  that, 
it  still  would  not  be  visible  at  such  a  distance,  even  if  we 
neglect  the  well-known  concealing  or  blinding  effect  of  the 
rays  of  a  bright  star  when  the  observer  is  trying  to  view  a 
faint  one  close  to  it.  Clearly,  then,  the  obscure  objects 
seen  by  Dr.  See  near  some  of  the  stars,  if  they  really  are 
bodies  visible  only  by  light  reflected  from  their  surfaces, 
must  be  enormously  larger  than  the  planet  Jupiter,  and 
can  not,  accordingly,  be  admitted  into  the  category  of 
planets  proper,  whatever  else  they  may  be. 

Perhaps  they  are  extreme  cases  of  what  we  see  in  the 
system  of  Sirius — i.  e.,  a  brilliant  star  with  a  companion 
which  has  ceased  to  shine  as  a  star  while  retaining  its 
bulk.  Such  bodies  may  be  called  planets  in  that  they  only 
shine  by  reflected  light,  and  that  they  are  attached  to  a 
brilliant  sun;  but  the  part  that  they  play  in  their  systems 
is  not  strictly  planetary.  Owing  to  their  great  mass  they 
bear  such  sway  over  their  shining  companions  as  none  of 
our  planets,  nor  all  of  them  combined,  can  exercise;  and 
for  the  same  reason  they  can  not,  except  in  a  dream,  be 
imagined  to  possess  that  which,  in  our  eyes,  must  always 
be  the  capital  feature  of  a  planet,  rendering  it  in  the 
highest  degree  interesting  wherever  it  may  be  found- 
sentient  life. 

It  does  not  follow,  however,  that  there  are  no  real 
planetary  bodies  revolving  around  the  stars.  As  Dr.  See 
himself  remarks,  such  insignificant  bodies  as  our  planets 
could  not  be  seen  at  the  distance  of  the  fixed  stars,  "  even 
if  the  power  of  our  telescopes  were  increased  a  hundred- 
fold, and  consequently  no  such  systems  are  known." 

This  brings  me  to  another  branch  of  the  subject.  In 
the  same  article  from  which  I  have  already  quoted  (Recent 
Discoveries  respecting  the  Origin  of  the  Universe,  Atlantic 


188  PLEASURES  OF  THE  TELESCOPE 

Monthly,  vol.  Ixxx,  pages  484-492),  Dr.  See  sets  forth  the 
main  results  of  his  well-known  studies  on  the  origin  of  the 
double  and  multiple  star  systems.  He  finds  that  the  stel- 
lar systems  differ  from  the  solar  system  markedly  in  two 
respects,  which  he  thus  describes: 

"1.  The  orbits  are  highly  eccentric;  on  the  average 
twelve  times  more  elongated  than  those  of  the  planets  and 
satellites. 

"  2.  The  components  of  the  stellar  systems  are  fre- 
quently equal  and  always  comparable  in  mass,  whereas 
our  satellites  are  insignificant  compared  to  their  plan- 
ets, and  the  planets  are  equally  small  compared  to  the 
sun." 

These  peculiarities  of  the  star  systems  Dr.  See  ascribes 
to  the  effect  of  "  tidal  friction,"  the  double  stars  having 
had  their  birth  through  fission  of  original  fluid  masses 
(just  as  the  moon,  according  to  George  Darwin's  theory, 
was  born  from  the  earth),  and  the  reaction  of  tidal  fric- 
tion having  not  only  driven  them  gradually  farther  apart 
but  rendered  their  orbits  more  and  more  eccentric.  This 
manner  of  evolution  of  a  stellar  system  Dr.  See  contrasts 
with  Laplace's  hypothesis  of  the  origin  of  the  planetary 
system  through  the  successive  separation  of  rings  from 
the  periphery  of  the  contracting  solar  nebula,  and  the 
gradual  breaking  up  of  those  rings  and  their  aggregation 
into  spherical  masses  or  planets.  While  not  denying  that 
the  process  imagined  by  Laplace  may  have  taken  place 
in  our  system,  he  discovers  no  evidence  of  its  occurrence 
among  the  double  stars,  and  this  leads  him  to  the  follow- 
ing statement,  in  which  believers  in  the  old  theological 
doctrine  that  the  earth  is  the  sole  center  of  mortal  life  and 
of  divine  care  would  have  found  much  comfort: 

"  It  is  very  singular  that  no  visible  system  yet  dis- 
cerned has  any  resemblance  to  the  orderly  and  beautiful 


ARE  THERE  PLANETS  AMONG  THE  STARS?  189 

system  in  which  we  live;  and  one  is  thus  led  to  think  that 
probably  our  system  is  unique  in  its  character.  At  least 
it  is  unique  among  all  known  systems." 

If  we  grant  that  the  solar  system  is  the  only  one  in 
which  small  planets  exist  revolving  around  their  sun  in 
nearly  circular  orbits,  then  indeed  we  seem  to  have  closed 
all  the  outer  universe  against  such  beings  as  the  inhabit- 
ants of  the  earth.  Beyond  the  sun's  domain  only  whirling 
stars,  coupled  in  eccentric  orbits,  dark  stars,  some  of  them, 
but  no  planets — in  short  a  wilderness,  full  of  all  energies 
except  those  of  sentient  life!  This  is  not  a  pleasing  pic- 
ture, and  I  do  not  think  we  are  driven  to  contemplate  it. 
Beyond  doubt,  Dr.  See  is  right  in  concluding  that  double 
and  multiple  star  systems,  with  their  components  all  of 
magnitudes  comparable  among  themselves,  revolving  in 
exceedingly  eccentric  orbits  under  the  stress  of  mutual 
gravitation,  bear  no  resemblance  to  the  orderly  system  of 
our  sun  with  its  attendant  worlds.  And  it  is  not  easy  to 
imagine  that  the  respective  members  of  such  systems 
could  themselves  be  the  centers  of  minor  systems  of 
planets,  on  account  of  the  perturbing  influences  to  which 
the  orbits  of  such  minor  systems  would  be  subjected. 

But  the  double  and  multiple  stars,  numerous  though 
they  be,  are  outnumbered  a  hundred  to  one  by  the  single 
stars  which  shine  alone  as  our  sun  does.  What  reason 
can  we  have,  then,  for  excluding  these  single  stars,  consti- 
tuting as  they  do  the  vast  majority  of  the  celestial  host, 
from  a  similarity  to  the  sun  in  respect  to  the  manner  of 
their  evolution  from  the  original  nebulous  condition? 
These  stars  exhibit  no  companions,  such  planetary  at- 
tendants as  they  may  have  lying,  on  account  of  their 
minuteness,  far  beyond  the  reach  of  our  most  powerful  in- 
struments. But  since  they  vastly  outnumber  the  binary 
and  multiple  systems,  and  since  they  resemble  the  sun  in 


190  PLEASURES  OF  TEE  TELESCOPE 

having  no  large  attendants,  should  we  be  justified,  after 
all,  in  regarding  our  system  as  "  unique  "?  It  is  true  we 
do  not  know,  by  visual  evidence,  that  the  single  stars  have 
planets,  but  we  find  planets  attending  the  only  representa- 
tive of  that  class  of  stars  that  we  are  able  .to  approach 
closely — the  sun — and  we  know  that  the  existence  of 
those  planets  is  no  mere  accident,  but  the  result  of  the 
operation  of  physical  laws  which  must  hold  good  in  every 
instance  of  nebular  condensation. 

Two  different  methods  are  presented  in  which  a  rotat- 
ing and  contracting  nebula  may  shape  itself  into  a  stellar 
or  planetary  system.  The  first  is  that  described  by  La- 
place, and  generally  accepted  as  the  probable  manner  of 
origin  of  the  solar  system — viz.,  the  separation  of  rings 
from  the  condensing  mass,  and  the  subsequent  transfor- 
mation of  the  rings  into  planets.  The  planet  Saturn  is 
frequently  referred  to  as  an  instance  of  the  operation  of 
this  law,  in  which  the  evolution  has  been  arrested  after 
the  separation  of  the  rings,  the  latter  having  retained  the 
ring  form  instead  of  breaking  and  collecting  into  globes, 
forming  in  this  case  rings  of  meteorites,  and  reminding  us 
of  the  comparatively  scattered  rings  of  asteroids  sur- 
rounding the  sun  between  the  orbits  of  Mars  and  Jupiter. 
This  Laplacean  process  Dr.  See  regards  as  theoretically 
possible,  but  apparently  he  thinks  that  if  it  took  place  it 
was  confined  to  our  system. 

The  other  method  is  that  of  the  separation  of  the 
original  rotating  mass  into  two  nearly  equal  parts.  The 
mechanical  possibility  of  such  a  process  has  been  proved, 
mathematically,  by  Poincare'  and  Darwin.  This,  Dr.  See 
thinks,  is  the  method  which  has  prevailed  among  the 
stars,  and  prevailed  to  such  a  degree  as  to  make  the  solar 
system,  formed  by  the  ring  method,  probably  a  unique 
phenomenon  in  the  universe. 


ARE  THERE  PLANETS  AMONG  TEE  STARS?  191 

Is  it  not  more  probable  that  both  methods  have  been 
in  operation,  and  that,  in  fact,  the  ring  method  has  oper- 
ated more  frequently  than  the  other?  If  not,  why  do  the 
single  stars  so  enormously  outnumber  the  double  ones? 
It  is  of  the  essence  of  the  fission  process  that  the  resulting 
masses  should  be  comparable  in  size.  If,  then,  that  pro- 
cess has  prevailed  in  the  stellar  universe  to  the  practical 
exclusion  of  the  other,  there  should  be  very  few  single 
stars;  whereas,  as  a  matter  of  fact,  the  immense  majority 
of  the  stars  are  single.  And,  remembering  that  the  sun 
viewed  from  stellar  distances  would  appear  unattended 
by  subsidiary  bodies,  are  we  not  justified  in  concluding 
that  its  origin  is  a  type  of  the  origin  of  the  other  single 
stars? 

While  it  is,  as  I  have  remarked,  of  the  essence  of  the 
fission  process  that  the  resulting  parts  of  the  divided  mass 
should  be  comparable  in  magnitude,  it  is  equally  of  the 
essence  of  the  ring,  or  Laplacean  process,  that  the  bodies 
separated  from  the  original  mass  should  be  comparatively 
insignificant  in  magnitude. 

As  to  the  coexistence  of  the  two  processes,  we  have, 
perhaps,  an  example  in  the  solar  system  itself.  Darwin's 
demonstration  of  the  possible  birth  of  the  moon  from  the 
earth,  through  fission  and  tidal  friction,  does  not  apply  to 
the  satellites  attending  the  other  planets.  The  moon  is 
relatively  a  large  body,  comparable  in  that  respect  with 
the  earth,  while  the  satellites  of  Jupiter  and  Saturn,  for 
instance,  are  relatively  small.  But  in  the  case  of  Saturn 
there  is  visible  evidence  that  the  ring  process  of  satellite 
formation  has  prevailed.  The  existing  rings  have  not 
broken  up,  but  their  very  existence  is  a  testimony  of  the 
origin  of  the  satellites  exterior  to  them  from  other  rings 
which  did  break  up.  Thus  we  need  not  go  as  far  away 
as  the  stars  in  order  to  find  instances  illustrating  both 


192  PLEASURES  OF  THE  TELESCOPE 

the  methods  of  nebular  evolution  that  we  have  been  deal- 
ing with. 

The  conclusion,  then,  seems  to  be  that  we  are  not  justi- 
fied in  assuming  that  the  solar  system  is  unique  simply 
because  it  differs  widely  from  the  double  and  multiple 
star  systems;  and  that  we  should  rather  regard  it  as 
probable  that  the  vast  multitude  of  stars  which  do  not 
appear,  when  viewed  with  the  telescope,  or  studied  by 
spectroscopic  methods,  to  have  any  attendants  compara- 
ble with  themselves  in  magnitude,  have  originated  in  a 
manner  resembling  that  of  the  sun's  origin,  and  may  be 
the  centers  of  true  planetary  systems  like  ours.  The 
argument,  I  think,  goes  further  than  to  show  the  mere 
possibility  of  the  existence  of  such  planetary  systems  sur- 
rounding the  single  stars.  If  those  stars  did  not  origi- 
nate in  a  manner  quite  unlike  the  origin  of  the  sun,  then 
the  existence  of  planets  in  their  neighborhood  is  almost 
a  foregone  conclusion,  for  the  sun  could  hardly  have 
passed  through  the  process  of  formation  out  of  a  rotating 
nebula  without  evolving  planets  during  its  contraction. 
And  so,  notwithstanding  the  eccentricities  of  the  double 
stars,  we  may  still  cherish  the  belief  that  there  are  eyes 
to  see  and  minds  to  think  out  in  celestial  space. 


INDEX 


NOTE. — Double,  triple,  multiple,  and  colored  stars,  star  clusters,  nebulae,  and  temporary 
stars  will  be  found  arranged  under  the  heads  of  their  respective  constellations. 


ANDROMEDA,  Map  No.  24, 125. 
Stars :  o,  126. 
7,  128. 
/t,  126. 
36,  128. 

Temporary  star  :  1885,  127. 
Cluster :  457,  128. 
Variable :  R,  128. 
Nebula :  116,  126. 
AQUARIUS,  Map  No.  18, 107. 
Stars :  £  106. 
T,  108. 
*,  108. 
41, 106. 
2  2729, 106. 
2  2745  (12),  106. 
2  2998, 108. 
Variables:  R,  108. 
S,  108. 
T,  106. 
Nebute :  4628  (Rosse's  "  Saturn  "),  108. 

4678,  108. 

AQUILA,  Map  No.  16,  95. 
Stars :  »,  94. 
11,  94. 
23,  94. 
57,  94. 
2  2644,  94. 
2  2544,  94. 
Cluster :  4440,  94. 
Variables :  17,  94. 
R,  94. 

ARGO  :  Map  No.  2,  31 ;  Map  No.  7,  55. 
Stars :  2  1097,  33. 

2  1146  (5),  35. 
Clusters :  1551,  35. 


Clusters :  1564,  35. 
1571,  35. 
1630,  56. 

Nebula :  1564,  35. 
ARIES,  Map  No.  22, 119. 
Stars :  7,  118. 
€,  120. 
X,  118. 

IT,   118. 

14,  118. 
30,  118. 
41,  118. 
52,  120. 
2  289,  118. 

AURIGA,  Map  No.  5,  45. 
Stars :  a  (Capella),  44. 

0  (Menkalina),  46. 
e,  50. 

0,  48. 
\,  50. 
14,  50. 
26,  50. 
41,  51. 

2  616,  48. 

Temporary  star  :  1892,  48. 
Clusters :  996,  51. 
1067,  51. 
1119,  51. 
1166,  51. 
1295,  48. 

BOOTES,  Map  No.  11,  67. 
Stars :  a  (Arcturus),  66. 
8,  71. 

e  (Mirac),  71. 
£70. 

1,  71. 

193 


194: 


PLEASURES  OF  THE  TELESCOPE 


Stars :  «,  71. 
A*,  71. 

e,m 

IT,  70. 

2  1772,  70. 
2  1890  (39),  71. 
2  1909  (44),  71. 
2  1910  (279),  70. 
2  1926,  71. 

CAMELOPARDALUS,  Map  No.  25, 133. 
Stars :  1,  134. 
2,  134. 
7,  135. 
2  385,  134. 
2  390,  134. 
Cluster :  940,  135. 
CANES  VENATICI,  Map  No.  26, 137 ;  Map 

No.  11,  67. 
Stars:  2,136. 

12  (Cor  Caroli),  136. 
2  1606,  136. 
2  1768  (25),  72. 
Cluster :  3936,  72. 
Nebula :  3572, 136. 
CANIS  MAJOR,  Map  No.  2,  31. 
Stars :  a  (Sirius),  30. 
5,33. 
/t,33. 

Clusters :  1454,  33. 
1479,  33. 
1512,  33. 
Variable :  7,  33. 
Nebula :  1511,  33. 
CANIS  MINOR,  Map  No.  3,  34. 
Stars :  a  (Procyon),  36. 
14,  36. 

2  1126  (31  Can.  Min.  Bode),  36. 
CANCER,  Map  No.  4,  39. 
Stars :  £  43. 
*,  44. 
66,44. 
2  1223,  44. 
2  1291,  44. 
2  1311,  44. 
Clusters :  Praesepe,  43. 

1712,  44. 

CAPRICORNUS,  Map  No.  13,  83 ;  Map  No. 
18, 107. 


Stars  :  a,  84. 

0,  85. 
o,85. 
*,  85. 

|  P,  85. 
<r,85. 

Cluster  :  4608,  85. 
CASSIOPEIA,  Map  No.  25,  133. 
Stars  :  i\,  132. 

1,  132. 
<r,  132. 
*,  132. 

Temporary     star:     1572     (Tycho's), 

134. 

Cluster  :  392,  134. 
CEPHEUS,  Map  No.  25,  133. 
CETUS,  Map  No.  20,  112. 
Stars:  o,  113. 
7,  113. 

'Cm. 

*?,  HI. 
26,  111. 
42,  111. 

Variables  :  o  (Mira),  111. 
R,  113. 
S,  113. 

COLUMBA,  Map  No.  2,  31. 
COMA  BERENICES,  Map  No.  6,  53. 
Stars:  2,54. 
12,  54. 
17,  54. 
24,54. 
35,  54. 
42,  54. 
Clusters  :  2752,  56. 

3453,  56. 

CORONA  BOREALIS,  Map  No.  11,  67. 
Stars  :  7,  72. 


v,  73. 
<r,  73. 

2  1932,  72. 

Temporary  star  :  1866,  73. 
CORVUS,  Map  No.  8,  58. 

Star  :  8,  57. 

CRATER,  Map  No.  8,  58. 
Variable  :  R,  57. 


INDEX 


195 


CYGNUS,  Map  No.  17,  99. 

Stars  :  7,  43. 

Stars:  0  (Albireo),  103. 

5,41. 

8,  104. 

6,43. 

A,  105. 

6.41 

p,  105. 

1,42. 

o«,  104. 

K,  40. 

X  (17),  104. 

A,  43. 

^,  104. 

M,43. 

49,  104. 

ir,  40. 

52,  104. 

15,  43. 

61,  105. 

38,  43. 

Temporary  star  :  1876,  105. 

Cluster:  1360,42. 

Cluster  :  4681,  105. 

Variables  :  £  41. 

Variable  :  x»  104. 

TJ,  42. 

DELPHINUS,  Map  No.  16,  95. 

E,  41. 

Stars:  a,  96. 

8,41. 

0,96. 

T,  41. 

7,94. 

U,41. 

DRACO,  Map  No.  15,  91  ;  Map  No.  26,  137. 

Nebula:  1532,41. 

Stars  :  7,  93. 

HERCULES,  Map  No.  14,  87  ;  Map  No.  15, 

6,93. 

91. 

*  93. 

Stars  :  a,  89. 

A*,  93. 

7,89. 

v,  93. 

5,  89. 

2  1984,  93. 

£89. 

2  2054,  93. 

«,  89. 

2  2078  (17),  93. 

/x,90. 

2  2323,  93. 

p,  90. 

Nebula:  4373,93. 

42,  90. 

4415,  94. 

95,  90. 

EQUULEUS,  Map  No.  18,  107. 

2  2101,  90. 

Stars  :  0,  109. 

2  2104,  90. 

7,  109. 

2  2215,  90. 

2  2735,  108. 

2  2289,  90. 

2  2737,  108. 

Nebulae  :  4230  (M  13),  92. 

2  2742,  108. 

4234,  92. 

2  2744,  108. 

HYDRA,  Map  No.  3,  34;  Map  No.  8,  58; 

ERIDANUS,  Map  No.  21,  115. 

Map  No.  10,  65. 

Stars  :  7,  114. 

Stars  :  o,  56. 

o2,  116. 

6,36. 

12,  114. 

0,36. 

2  470  (32),  114. 

Bu.  339,  56. 

2  516  (39),  114. 

2  1245,  36. 

2  590,  116. 

Variable  :  R,  59. 

Nebula:  826,  116. 

Nebulas  :  2102,  56. 

GEMINI,  Map  No.  4,  39. 

3128,  59. 

Stars  :  a  (Castor),  38. 

LACERTA,  Map  No.  17,  99. 

0  (Pollux),  40. 

LEO,  Map  No.  6,  53. 

196                        PLEASURES  OF  THE  TELESCOPE 

Stars:  7,  52. 

Stars  :  2  1183,  35. 

i,  52. 

2  1190,  35. 

T,  52. 

Clusters  :  1424,  35. 

49,52. 

1465,  36. 

54,  52. 

1483,  36. 

88,  52. 

1611,  36. 

90,  52. 

1637,  36. 

Variable  :  R,  52. 

Variable  :  S,  35. 

Nebula:  1861,52. 

OPHIUCHUS,  Map  No.  12,  77;  Map  No. 

LEO  MINOR,  Map  No.  26,  137. 

14,  87. 

LEPUS,  Map  No.  1,  21  ;  Map  No.  2,  31. 

Stars  :  A,  86. 

Stars  :  o,  30. 

T,  86. 

0,30. 

36,  79. 

7,30. 

39,  79. 

i,30. 

67,  86. 

45,  30. 

70,  86. 

Variable:  R,  29. 

73,  86. 

LIBRA,  Map  No.  10,  65. 

2  2166,  86. 

Stars  :  A,  64. 

2  2173,  86. 

a,  64. 

Temporary  star  :  1604,  80. 

0,64. 

Clusters:  4211,  79. 

i,64. 

4256,  88. 

Variable  :  8,  64. 

4264,  79. 

LYNX,  Map  No.  5,  45. 

4268,  79. 

Stars  :  4,  51. 

4269,  79. 

5,51. 

4270,  79. 

12,  51. 

4315,  88. 

14,  51. 

4346,  79. 

19,  51. 

4410,  88. 

38,  52. 

Variable  :  R,  80. 

2  958,  51. 

ORION,  Map  No.  1,  21. 

2  1009,  51. 

Stars  :  a  (Betelgeuse),  27. 

2  1333,  51. 

0  (Rigel),  20. 

LYRA,  Map  No.  17,  99. 

8,23. 

Stars  :  a  (Vega),  97. 

C,23. 

0,100. 

T;,  24. 

e,  98. 

0  (Trapezium),  25. 

£100. 

«,27. 

17,  103. 

A,  28. 

Variable  :  0,  100. 

P,  28. 

Nebula:  4447  (Ring),  102. 

<r,24. 

MONOCEROS,  Map  No.  1,  21  ;  Map  No.  3,  34. 

T,  28. 

Stars  :  4,  35. 

f>,  29. 

8,35. 

2  627,  28. 

11,  35. 

2  629,  28. 

2  921,  35. 

2  652,  28. 

2  938,  35. 

2  725,  24. 

2  950,  35. 

2  728  (A  32),  28. 

INDEX 


197 


Stars  :  2  729,  29. 
2  747,  27. 
2  750,  27. 
2  795  (52),  27. 
2  816,  29. 
0  2  98  (i),  28. 
Clusters :  905,  29. 
1184,  27. 
1361,  29. 
1376,  29. 

Nebula  :  Great  Orion  Nebula,  25. 
1227,  23. 
1267,  29. 

PEGASUS,  Map  No.  19, 110. 

Stars :  0, 109. 

7,  109. 

e,  109. 

TJ,  109. 

PERSEUS,  Map  No.  24, 125. 
Stars :  e,  129. 
C,  130. 
rj,  129. 

Clusters :  512,  129. 
521,  129. 

Variable  :  &  (Algol),  130. 
PISCES,  Map  No.  18,  107;  Map  No.  20, 

112  ;  Map  No.  22,  119. 
Stars :  a,  117. 
£  117. 
*,  H7. 
55,  117. 
65, 117. 
66,  117. 
77, 117. 

Variable :  R,  118. 
SAGITTA,  Map  No.  16,  95. 
Stars :  e,  94. 
C,94. 
0,94. 

Nebula :  4572,  94. 
SAGITTARIUS,  Map  No.  12,  77 ;  Map  No. 

13,  83. 
Stars :  /i,  80. 

54,  84. 

Clusters  :  M  25,  81. 
4355,  81. 
4361  (M  8),  81. 
4397  (M  24),  81. 


Clusters :  4424,  84. 

Variables :  R,  84. 

T,  84. 

U,  82. 

V,  82. 

SCORPIO,  Map  No.  12,  77. 
Stars :  a  (Antares),  75. 
ft  76. 
v,  76. 
1,76. 
tr,  76. 

Temporary  star  :  1860,  78. 
Clusters :  4173,  78. 
4183,  78. 
SCUTUM  SOBIESKH,  Map  No.  12,  77 ;  Map 

No.  13,  83. 
Stars:  22306,82. 
2  2325,  82. 
Clusters :  4400,  82. 
4426,  82. 
4437,  82. 
Variable :  R,  82. 
Nebula :  4441,  82. 
SERPENS,  Map  No.  12,  77 ;  Map  No.  14, 

87. 

Stars :  a,  86. 
ft  86. 
8,86. 
0,88. 
v,  86. 

Variable :  R,  86. 
TAURUS,  Map  No.  23, 121. 
Stars :  a  (Aldebaran),  123. 
TJ  (Alcyone),  120. 
0, 123." 
K,  123. 
<r,  124. 
T,  124. 
<J>,  123. 
X,  123. 
30,  122. 
2  412  (7),  120. 
2  430,  122. 
2  674,  124. 
2  716,  124. 

Clusters:  Hyades,  120. 
Pleiades,  120. 
1030,  124. 


198 


PLEASURES  OF  THE  TELESCOPE 


Variable :  \,  122. 
Nebulae  :  in  Pleiades,  120. 

1157  (Crab  Net),  124. 
TRIANGULUM,  Map  No.  24, 125. 
Star:  6,  129. 
Nebula :  352, 129. 
URSA  MAJOR. 
Stars:  £(Mizar),  135. 
i,  135. 
v,  135. 
f,  135. 
<r2,  135. 
23,  135. 
57,  135. 
65, 135. 

Nebulas :  1949,  136. 
1950,  136. 
2343,  136. 

URSA  MINOR,  Map  No.  26, 137. 
Stars :  a  (Pole  Star),  138. 

IT,  138. 

VIRGO,  Map  No.  9,  61. 
Stars :  a  (Spica),  59. 
7,59. 
0,60. 
84,  62. 
2  1669,  59. 
'   21846,62. 
Variables :  R,  63. 
S,  63. 
U,  63. 

Nebulas :  Field  of  the,  62. 
2806,  63. 
2961,  63. 
3105,  63. 

VULPECTTLA,  Map  No.  17,  99. 
Star:  22695,  106. 
Temporary  star :  1670,  106. 
Nebula :  4532  (Dumb  Bell),  106. 
THE  MOON,  most  interesting  of  telescopic 
objects,    156;   telescopic    views    of 
moon  reversed,  157. 
Craters,  ring  mountains,  and  ringed 
plains : 

Agatharchides,  179. 
Agrippa,  168. 
Albategnius,  171. 
Alhazen,  160. 


Aliacensis,  171. 
Alphonsus,  176. 
Archimedes,  175. 
Ariadaaus,  168. 
Aristarchus,  174. 
Aristillus,  167. 
Aristoteles,  162. 
Arzachel,  176. 
Atlas,  160. 
Autolycus,  167. 
Bailly,  178. 
Ball,  176. 
Barrow,  162. 
Beer,  175. 
Berzelius,  160. 
Billy,  179. 
Bullialdus,  180. 
Burckhardt,  157. 
Capuanus,  179. 
Cassini,  167. 
Catharina,  170, 
Cichus,  179. 
Clavius,  178. 
Cleomenes,  159. 
Condorcet,  160. 
Copernicus,  175. 
Cyrillus,  170. 
Delisle,  174. 
Endymion,  160. 
Eratosthenes,  175. 
Eudoxus,  162. 
Euler,  174. 
Firmicus,  160. 
Fracastorius,  169, 179. 
Furnerius,  161. 
Gassendi,  179. 
Gauss,  159. 
Geminus,  160. 
Goclenius,  169. 
Godin,  168. 
Grimaldi,  179. 
Guttemberg,  169. 
Hainzel,  179. 
Hansen,  160. 
Helicon,  174. 
Hell,  176. 
Hercules,  160. 
Herodotus,  174. 


INDEX 


199 


Herschel,  Caroline,  174. 
Hipparchus,  171. 
Humboldt,  161. 
Hyginus,  168. 
Julius  Caesar,  168. 
Kepler,  176. 
Lambert,  174 
Landsberg,  180. 
Langrenus,  160,  168. 
Letronne,  179. 
Leverrier,  174. 
Lexell,  176. 
Lichtenberg,  174. 
Linne,  165. 
Longoraontanus,  178. 
Macrobius,  159. 
Maginus,  178. 
Manilius,  166. 
Maurolycus,  172. 
Menelaus,  166. 
Mercator,  179. 
Mersenius,  179. 
Messala,  160. 
Messier,  169. 
Newton,  178. 
Petavius,  160, 168. 
Picard,  157. 
Piccolomini,  171. 
Pico,  172. 
Plato,  172. 
Plinius,  166. 
Posidonius,  163,  164. 
Proclus,  158. 
Ptoleraaaus,  176. 
Purbach,  176. 
Sacrobosco,  171. 
Schickard,  178. 
Schiller,  178. 
Silberschlag,  168. 
Stofler,  171. 
Sulpicius  Gallus,  166. 
Theaetetus,  167. 
Thebit,  176. 
Theophilus,  170. 
Timocharis,  174. 
Tobias  Mayer,  176. 
Tralles,  159. 
Triesnecker,  168. 


Tycho,  177,  178. 

Vendelinus,  160,  168. 

Vieta,  179. 

Vitello,  179. 

Walter,  171. 

Wargentin,  179. 

Werner,  171. 

Wilhelm  I,  178. 
Maria,  or  "  Seas  "  : 

Lacus  Somniorum,  163. 

Mare  Crisium,  157,  159,  160. 

Mare  Fecunditatis,  160,  168. 

Mare  Frigoris,  162,  172. 

Mare  Humboldtianum,  160. 

Mare  Humorum,  176,  179. 

Mare  Imbrium,  163,  172,  174. 

Mare  Nectaris,  168. 

Mare  Nubium,  176. 

Mare  Serenitatis,  163,  164,  165. 

Mare  Tranquilitatis,  168. 

Mare  Vaporum,  166,  167. 

Oceanus    Procellarum,    172,   176r 
179. 

Palus  Nebularum,  167. 

Palus  Putredinis,  167. 

Palus  Somnii,  159. 

Sinus  ^Estuum,  172. 

Sinus  Iridum,  172,  173. 
Other  formations : 

Alps  Mountains,  163. 

Apennine  Mountains,  163, 167, 175, 

Cape  Agarum,  158. 

Cape  Heraclides,  173. 

Cape  Laplace,  173. 

Carpathian  Mountains,  176. 

Caucasus  Mountains,  163. 

Cordilleras  Mountains,  180. 

D'Alembert  Mountains,  180. 

DOrfel  Mountains,  180. 

Haemus  Mountains,  165. 

Harbinger  Mountains,  174. 

Leibnitz  Mountains,  180. 

"  Lunar  Railroad,"  176. 

Mt.  Argjeus,  165,  167. 

Mt,  Hadley,  167. 

Mt.  Huygeus,  175. 

Pyrenees  Mountains,  169. 

Taurus  Mountains,  164. 


200 


PLEASURES  OF  TEE  TELESCOPE 


THE  PLANETS  :  Are  there  planets  among 

the  stars?  183. 
Mars,  two  views  of,  17. 

best  advertised  of  planets,  151. 

favorable  oppositions  of,  152. 

seen  with  5-inch  telescope,  152. 

polar  caps  of,  152. 
color  of,  152. 

dark  markings  on,  152. 
"canals,"  153. 

earthlike  condition  of,  153. 
Mercury,  phases  of,  155. 

peculiar  rotation  of,  155. 

markings  on,  155. 

probably  not  habitable,  155. 
Jupiter,  easiest  planet  for  amateurs,  141. 

seen  with  5-inch  glass,  141. 

satellites,  swift  motions  of,  142. 

velocity  of  planet's  equator,  142. 

how  to  see  all  sides  of,  142,  143. 

watching  rotation  of,  143. 

eclipses  and  transits   of    satellites, 
144,  147. 

belts  and  clouds  of,  145. 

different  rates  of  rotation,  145. 

names  and  numbers  of  satellites,  146. 
Saturn,  next  to  Jupiter  in  attractive- 
ness, 147. 

seen  with  5-inch  glass,  148. 

its  moons  and  their  orbits,  148,  149. 

polar  view  of  system,  149. 

Roche's  limit,  149, 150. 


Saturn,  origin  of  the  rings,  150. 

Pickering's  ninth  satellite,  151. 

the  satellites  as  telescopic  objects, 

151. 
Venus^her  wonderful  brilliance,  153. 

her  atmosphere  seen,  153. 

Lowell's  observations,  153. 

Schiaparelli's  observations,  154. 

her  peculiar  rotation,  154. 

how  to  see,  in  daytime,  155. 
Neptune  and  Uranus,  155. 
THE  SUN,  181. 
shade  glasses  for  telescopes  in  viewing, 

181. 

solar  prism,  181. 
helioscope,  181. 
periodicity  of  spots,  181. 
to  see,  by  projection,  182. 
spectroscope  for  solar  observation,  182. 
THE  TELESCOPE: 
refractors  and  reflectors,  2,  8. 
eyepieces,  6,  9, 10. 
aberration  (chromatic),  6;  (spherical), 

6,17. 
achromatic  telescopes,  how  made,  7. 

object  glass,  8. 
magnifying  power,  11. 
mountings,  12. 
rules  for  testing,  13. 
image  of  star  in,  14. 
image  in  and  out  of  focus,  14,  15, 17. 
astigmatism,  16. 


THE  END 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  fcORRWED 
LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below,  or 

on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


28Ju!'58BB 


LD 


J1JL191962 


JUL131958 


OQT  10  S5U 


'60CT 

EC'^ 


REC'D  LD 


DEC  11  1959 


REC'D  CD 


MAR  8     1963 


JUL  20  1979 


LD  21A-50m-8,'57 
(C8481slO)476B 


General  Library 

University  of  California 

Berkeley 


1692  S.     Pleasures  of  the  Telescope        GARRET?  P.  SERWSS 

This  book  says  to  the  amateur,  in  effect: — "What  if  you  have  not  all 
advantages  of  clock-work  and  observatory  equipment.  You  may  know  some- 
thing of  the  witchery  of  the  heavens  even  with  a  little  telescope  of  three  to  five 
inches  aperture  !  "  "Pleasures  of  the  Telescope  "  is  popular  in  style  rather 
than  technical.  For  setting  forth  ' '  the  chief  attractions  of  the  starry  heavens, " 
a  complete  set  of  star-maps  is  included,  showing  "  all  the  stars  visible  to  the 
naked  eye  in  the  regions  of  sky  represented,  and  in  addition  some  stars  that 
can  only  be  seen  with  optical  aid."  In  six  chapters  these  twenty-six  maps  are 
described  so  plainly  that  the  amateur  can  readily  find  all  the  interesting  star- 
groups,  clusters,  and  nebulae,  and  also  the  colored  or  double  stars.  In  the 
three  concluding  chapters  the  moon  and  planets  receive  special  consideration. 
In  the  opening  chapter  the  amateur  is  told  how  to  select  and  test  a  glass. 

Booklovers  Bulletin. 


